By observation, for some people, a crate engine makes sense. For others, they can do better themselves, which is fine, too. One of our Mopar club members bought a big-inch RB from a "big-time" crate engine builder. It didn't last past the water getting hot, unfortunately.
You can chase that "big name" engine builder or you can find a basic engine builder which has good tools, pays attention to details, uses OEM-level parts, and does quality assembly work, usually at lesser cost and good durability. In many cases, the stuff which some scorn as "rebuilder" parts are really quite good, IF you know WHAT to buy and from where. Reason I know this is from my machine shop associate/engine builder. For a stock application, you don't need forged pistons, cast will do just fine IF they are name brand cast, as Silvolite or KB, for example. Bearings can be "white box", rather than otherwise, but still be the same bearings at lesser cost (from the engine builder supply network). Finding a good crank grinder can be troublesome, though. Seems the younger operators don't know how to properly radius the fillets on a turned crank.
As for the "auto supply rebuilds", like the used-to-be $299.95 Chevy 350s, they usually have the least expensive stuff in them to hit that price point, come from an "out of area" mass rebuilder, and will do just fine in a used car lot situation, but probably see oil use increase at about 30K miles, rather than 80K+ miles.
NOW . . . it's one thing for a shop to have lots of higher-level machines (power hones, etc.), but if they don't know how to do that procedure and read the "load factor" gauge, you can ruin an excellent bore quickly. In many cases, a simple boring bar, deck plates, and dingle-berry final hone can do just as well, if not better. On the bottom end, checking the main bearing bores for size and such, then the final line hone procedure, take care of that area. Getting the ring gaps to spec, grinding if necessary. Doing a good valve job, AFTER doing the valve guides (a good time to do the bronze helicoil type guide inserts). Verifying the stem-to-guide clearance will result in better oil consumption issues and longer "valve job" life. Stock umbrella valve seals, orange silicone OEM.
Piston rings? OEM-spec moly-filled compression rings and OEM-spec matching rings. Slick bore finish rather than rough, especially with the moly-filled rings.
You can get the short block assembled by the builder, have the heads done, too, but not installed, possibly, or let them do the complete long block. You add the intake manifold and other external "dress" items. Use the pre-lube shaft to pressure up the oil system before the engine fires.
As for engine builders, check with the local drag racers, but try to lean toward Mopar racers, if possible. When you talk to many who mention the same place, that's where to start, but not especially end there. There are lots of good engine builders, some even great, who don't have all of the trappings of a fancy shop, but it's the quality of the machine work AND a competent assembler that make things work.
Most machine shops will warranty the engine for what they did, but NOT for what YOU do. You can spec what you want in it, but let them get the parts. Reason is that if something doesn't work, THEY can fix it rather than waiting for YOU to go through channels to get it fixed. Their way, they know what's happening themselves and the down-time is usually less for them.
On what you've got already, if you start pulling it apart for this or that, you'll end up with a complete teardown and rebuild. As for the "70K needing a build", not quite accurate. It was a known fact that Chrysler usually set things up a little tighter than other OEMs did, for longer life, but would cost a little horsepower by comparison. So that "70K blueprint" is just getting things "right" rather than "worn out". Put a new double-roller timing chain (Mopar Perf or Cloyes) if you don't do anything else!
There CAN be some minor differences in the model year of the blocks. Relating to power steering pump mountings, etc. So getting a ready-built short block might have some issues if it's a different model year.
As for piston sizing, it can usually take an overbore of .030" to get to "clean" metal, to get rid of the old wear surfaces for a new, round cylinder bore. Replacement pistons are usually a little heavier than OEM pistons, so balancing will need to happen.
In DFW, we've got lots of engine builders, even some great ones. Plus a good many major drag racers shops. But to me, the key thing is to request OEM-level parts (pistons, rings, bearings, seals) and let the shop source them from their suppliers. Pistons can be problematic, due to the decrease in compression height, but a little of this can be regained with head surfacing. OEM-spec clearances, too. Solid machine work.
IF things don't work right, STOP and see what's going on! There's not any hard, fast rules of finding a good engine builder, unfortunately. If Mopar Perf still sold 440/375 crate motors, I"d recommend that, but then they are probably contracting with somebody to build them with their parts, IF they were still selling them. Otherwise, you're on your own.
CBODY67
