Car is pretty much a Frankenstein. Originally 71 318 duster. Was my brother’s since late 70’s and swapped in a 340 from a 68 barracuda. Rear from a 73, A body(3:55 posi). I believe it has a 904 3spd transmission. A friend of his back in the day out a high lift cam 850 carb which made no sense. As I grew up learning about cars in general I’ve done some work to it in time. As he’s getting older, I want to build a solid street able motor. The 68 340 ran just fine before engine was removed. Plan on taking heads(x heads) and inspecting. It does not have the hardened seats and have read that people still run unleaded gas and not worry. Then again if I’m going to replace seats with hardened and springs/retainers and possible guides if needed might as well just get an aftermarket? Any recommendations on brands? If able to stay with stock seats, obviously I’d change springs and check guides. Can anyone recommend a cam with either stock X head or cam/head combo. Has an edelbrock rpm intake manifold and I believe last 650 Holley carb which replaced the 850 which it used to have. Is there a cheap alternative to the 904 that would fit stock location and transfer of parts or just build the 904? Any recommendation for converter? I know 727 are hard to come by. Would a 46re from a 2wd ram fit in stock location of 71 duster? Any help on recommendation for replacement parts such as head gaskets, head bolts. Cam springs. As for lifters are hydraulic flat tappets better than solid lifters? I’ve been reading lately as of brand new cam/ lifter failures from cheap material regardless where it’s bought.