The possible dynamics I see in the OP's question are very innocent, seeking advice to possibly verify what some of the OP's friends/associates (who seem to know about cars) have suggested. Which can be problematic as I also suspect there might be a knowledge gap between them and those of us in here.
The many issues mentioned above (heavier torsion bars, trans, rear axle, brakes, etc.) weren't involved in the OP's received suggestions. Just putting something in there that's more powerful than what's already there. No more, no less. A reasonable response from some early "car people", I suspect. BTAIM
In the 1950s-era world of "hot rodding", it was somewhat common to source engines from a local/regional salvage yard. If you needed an engine right then, you went there and dealt with what they had. Or if you had some time, you shopped other yards. IF you were adventurous and had some basic mechanical skills (especially welding), many different engines could end up in places they didn't come in. I remember an old JCWhitney catalog and all of the (Ansen?) bellhousings to adapt every engine to a vehicle's existing manual transmission. The sky seemed to be the limit as to what was physically possible to be done. NOT respective of if it would make a vehicle that was really safe to drive, but if it moved and laid rubber, that was an improvement. So we can't dismiss that history, which tended to decrease a good bit as more vehicles came with larger factory-optional engines.
In more modern times, many perceive that all vehicles are generic and all related engines are similarly generic. Everything fits in everything else, in effect. WE know it's not that way at all. Hopefully, the OP can research and discover that things are not nearly as simple as many might suspect in any major vehicle possible modifications. It all looks so simple and quick on TV, but it's not nearly like that in real life.
Finding good mentors is always important. Only thing is that it can take some time to get to the "good/better/best" group. On the surface, one group can look as good as the next, unfortunately. I've seen that happen several times, even being a part of that situation in seeking credible/reliable information on other brands of vehicles, expanding my knowledges in the process. Unfortunately, it doesn't happen overnight!
@Vinsanity, welcome to one of the best knowledge bases on Chrysler Corp C-body (and some other platforms) on the net. A diverse group, to say the least. Hang around, look, watch, and learn. It can become a little addictive, too! Ask questions as desired as that's how learning can happen. It CAN be a big learning curve, but worth it.
Enjoy!
CBODY67
