To convert a /6 FMJ to a small block:
You will need either a V8 K-frame or the Schumacher mount kit (either one works well).
Throttle cable (There may be other manufacturers, but Pioneer still makes new cables: CA-8414 for 2-bbl or CA-8422 for 4-bbl).
Transmission kickdown linkage (3-piece or an aftermarket cable system). 2-bbl setups are easy to find. 4-bbl 3-piece setups, not so easy (or cheap) to find. If you are going 4-bbl, I recommend getting an aftermarket cable setup (unless you have already a source for parts).
A V8 1-piece kickdown linkage system will not work in most FMJ cars.
Wiring harness (or harness modifications – mainly for distributor pickup and engine oil pressure sender(s)).
If the /6 had factory A/C and/or a towing package, it should already have the wide radiator/core support brackets welded in.
Cars without A/C and without a towing package (like my ’77 318 wagon) – come with the narrow radiator/core support brackets welded in.
If your car has the narrow radiator and you wish to go with the wider radiator (like I do), you will need to either make brackets (like what M_Body_Coupe made – BTW, nice work!), modify the existing core support brackets (Note: look, measure, look, measure and re-look and re-measure before any cutting) OR replace the two pieces/brackets with A/C parts (takes a bit of welding to perform this task).
My plan is to perform the later, that is when I also get ready to modify the firewall (for A/C) and modify the transmission tunnel) for 5 or 6-speed manual conversion).
Most /6 radiators has necks in different locations than V8’s have – so a different radiator might be needed.
Note: there are a lot of V8 FMJ cars out there with a narrow radiator, so if you are not planning on using A/C, a narrow radiator might be fine.
The transmission cooler lines will be different. There are companies who make repop cooler lines – or you can get that from another parts car.
Pretty much all pulleys and brackets from a donor V8 car.
The torsion bars and sway bars are the same – but you might need to crank up the torsion bars for the additional weight of the V8. Brakes will also be the same.
Perform a search in forums for ride height adjustment or look in a FSM (Factory Service Manual).
Note: I would perform a ride height measurement BEFORE any work is performed, so you can know where to adjust car back too, AFTER repairs have been performed.
BudW
P.S. take plenty of pictures (like 200?) from your donor car before and during part removal.
Also, bag and tag your bolts, etc. It is more work but trust me, it will pay for itself in the end.
Also, post pictures of your progress and/or post questions you have during your project.