1+ year old, but maybe didn't get much activity due to not being in the 'wanted' section.
It can be a pain trying to collect all the missing pieces for sure. But it does help prevent sticker shock of buying a complete kit. YMMV
Bellhousings & trans come in a variety of types and you need to make sure to get the right trans for the chassis.
65 uses ball & trunnion output shaft, and 66-up is typical slip-yoke. 65 C-body reportedly also has a different mounting cast into the tailhousing, but I've never personally reviewed that.
Then get the right shifter for the trans, then shifter handle for the seat (whether buckets, console, or bench seat). Earlier trans use bolt-on handles, later ones use a clip-in (fewer handle options exist for the clip-ins)
C-body floor humps come in 2 styles, 65 uses a squarish-topped one, 65-68 uses an ovaled one. They are likely interchangeable provided you get the right boot and carpet.
Then the correct bellhousing, must fit the engine of course, but then the pilot/centering hole must match the trans (either 3.54", 4.805", or 5.125" for the OD units).
There is some flexibility - you can get adapter rings to fill gaps between larger bell-holes vs smaller trans bearing retainer, and IIRC the bearing retainers can be swapped on the 4.8 and 5.125". Cannot change the retainer on the 3.54" because the bolt circle is smaller.
The 10.5" bellhousing is a better choice as flywheels (130 tooth) are readily available vs the 11" (143-tooth). I've heard that 10.5" flywheels fit all V8 engines if they are neutral-balanced, and that a 10.95" scalloped clutch can be used if greater capacity is required. 11" flywheels are on some bigblocks, probably Hemis, and 360 trucks (externally-balanced) - so you need to ensure correct ID with them.
Bellhousing fitment to chassis is fuzzy for me - there are a variety of different types, specific to A, B, C, or E-body, likely due to where the Z-bar pivot ball attaches. Whether a guy could make a special adapter plate to teh correct location is unknown to me. Seems liek it should be possible, but won't know until it's in the car, and you're really invested at that point if it cannot be done.
You'll need the Z-bar next, and those a C-body specific, and v8 and 6yl bars differ also. The 6cyl bar is longer at the bellhousing and can be shortenend, though.
The linkage from Z-bar to trans clutch fork (BTW, you'll need the fork!) is common to 4-speed cars and replacement parts used to be available (maybe still are).
The rod from Z-bar to clutch pedal is C-body specific, of course, as is the pedal asembly. There are 2 types of those, depending on whether for power or manual brakes.
Then, on top of all of that, there's the crank drilling for the pilot bushing for the trans input shaft. Reportedly all steel-crank bigblocks are drilled, but I've also heard sometimes not honed to size for the bushing, and/or sometimes not drilled deep enough for the input shaft. I've never been able to confirm any of that. One option is a larger 3.9-5.2-5.9 Magnum roller bearing that fits in the bore for the torque converter snout. This will work, but some folks dislike using a roller bearing in that application, as it has no inner race and the rollers ride directly on the input shaft. That style was used in the Magnum engines, however the factory might've spec'd input shafts differently to make that robust. Might've used better surface hardness/finish, and an 833 shaft is surely a bit tarnished at this point.
Anyway, if you're still around, hopefully that helped.
