Just work with what you have and do it a step at a time if you want. No need to spend $$$ to have a fun solid car. Do you want a cruiser or drag car - which is what I see being thrown your way.
Cubic inches will always increase TORQUE and torque is what moves the car, not horsepower. You can have big cubes that spin 5500-5800 RPM's to keep the wear on the engine down or build a high RPM 6500-7000 RPM engine that is going to wear quicker. Do you want longevity or look to rebuild/refresh parts every once in a while?
Both bigger cubes and/or higher RPM's will need more air flow, ie bigger CFM's. The trade off with bigger CFM's is the loss of bottom end RPM's for an increase in upper RPM's. Thus the NEED for higher stall converters and better rear axle ratio's to compensate - also sucking up more gas to cruise around.
Now with bigger cubes/higher RPM engines, you will need to match a good cam having long duration and high lift. The longer the duration and often with more lift, you move your effective RPM range higher - once again killing low speed RPM's which most cars used for crusing run in. Best would of course be a roller cam, but these are expensive.
Now if you have deep pockets, a budget is not important, and your idea of cruising is a street/strip or race car, then by all means build the crap out of your car. But don't forget, with all the extra torque and HP, your trans will most likely NOT hold up to the extra wide and soft compound tires needed to get any kind of traction rather than smoke tires when you nail it. Of course the rear end really needs to be swapped with an 8 3/4 unit if you have the 8 1/4 rear. But if you do have the 8 3/4, you will need to upgrade it with HD axles, posi, bearings, etc. The stock suspension probably won't do you justice so anticipate mods in this area as well so you can plant all that torque and HP to the ground rather than experience spring wind-up, wheel hop, or broken universals.
It is often easy for others to build your engine for you on paper and tell you what is best because they are not paying for it. So yes, buy the stroker kit and get the best lightweight crank, light weight forged pistons & tool steel wrist pins, and forged rods. Buy the best 440 head flowing 340 CFM's so you can spin 7,000 RPM's and load up the 3.90 gears against a 3500 RPM stall converter. Stick the best single plane intake on there with an 1100CFM Holley and of course some 2 1/4" headers so all of it can breathe. Better yet, just buy a crate engine for 10K and be done with it.
Or...........you can enhance what you already have, increase torque and HP and have a car you can slap the pedal to the floor and pull ahead like never before and keep your costs down. This stuff is not rocket science and Mopars were among some of the best street racers in the 60's and 70's. MANY articles were written of them in many of the magazines of the day. They told you what to do to increase performance - tried and true. Get on Ebay in the magazine back issues section and grab some of these on the 383/400 engine build. The Direct Connection parts catalog from 1978 has all the parts needed to make the 383/400 into a 14 second bracket car, 13 second bracket car, and a 12 second bracket car. Very simple builds - dual exhaust/cast iron type like Road Runner, viscous fan, windage tray, electronic ignition kit or recurve your distributor, purple camshaft P3690214, HD valve springs, 1970-'71 383 Holley or 400CI Thermoquad, 1/2"-3/4" spacer when using the TQ, shift improver kit, 4.10 gears, sure grip, 9" x 28" slicks. It is not until you get into the 13 second bracket that I see the mention of 1968-'77 heads with 2.08" intakes & 1.74" exhaust valves and a good 3-angle valve job - no mention of aluminum heads or specially prepped/flowed heads, just plain old stock iron heads. Of course more aftermarket parts go into the 13 second car.
Here you can see that it does not take much to wake up a 383 at a level that will give great performance and yet still be streetable. A 14 second car is respectable. 13 seconds is better, but is a bigger trade off in streetability and gas mileage and will require more $$$. I would NOT install 4.10 gearing, but I would first install a "tight" 2500 RPM stall with the 2.73 gearing to see how you like it. If still not enough off the line, THEN I would swap up to a 3.23, keeping in mind that you will be raising your cruising RPM's on the highway at 70 MPH and may not like running your engine that high - and of course mileage will suffer. You may or may not get traction when you nail the pedal to the floor from a stop.
So get on Ebay and collect a few magazine articles or the Direct Connection parts catalog, and a few Mopar engine build books and educate yourself on building your engine your way with your dollars.