The reason why people do LS swaps (or any crate engine, for that matter) is because it is FAR cheaper to buy a brand new engine, or very low milage engine, and have it produce whatever horsepower they want, right out of the box. Whereas, if they actually built and engine, they'd spend 2-3k more, depending on what it is they want to do with it. You can buy a brand new crate small block from GMPP, or Summit, from anywhere between $2200-$4000, that makes every bit of 400hp right out of the box. Or more, depending on what engine choice you have. Even just buying the short block is worth the money. Instead of sending your crank out to get turned and balanced (with the rods and pistons for balancing), having your block clean/inspected/sonic inspected/bored/honed/decked/deburred/align bored, then to buy all new cam/main/rod bearings, freeze out plugs, misc gaskets and seals, yadda yadda yadda... You'd spend more then the crate bottom end already assembled. Then it's just a matter of choosing your heads, cam, intake, etc... And, if your stock crank is not a forged unit, a new forged crank can run easily $600.
My AMC 360 will roughly cost the folling: an easy $1000 for K1 forged rods and Wiseco forged pistons. $1700 for Edel aluminum heads. $300 for Edel Performer RPM Air Gap intake. If I stick with the Edel cam/push rods/timing chain and gear set, that's roughly $400 (from memory). That all adds up to $3400 thus far. Then there is a GOOD HEI dist, GOOD harmonic balancer, flywheel, carb, gaskets/seals, updated timing cover, water pump, oil pump, Milodon oversize oil pan, sending the crank and block out, plugs, wires, etc, etc, etc, etc, etc......... All adds up to every bit of $6k. But, I have no choice because you have to build what you have when it comes to an AMC. I could swap in a small block Chevy, either crate engine, or, build it myself, and save probably $2k-$3500 depending on which route for a small block. Or do the ver popular LS swap. I don't particularly care to do this because it's not "true" to the car. I don't really care to see LS engine swapped into older GM cars/trucks because that's not what it came with. Unless you absolutely NEED to make 700+hp does an LS engine have to be swapped in, in MY opinion. Not that a small or big block Chevy can't make those numbers, it's just that the technology in the LS series is FAR superior and more streetable.
But, back to my car for a moment, lol. If I use the complete Edelbrock Performer RPM package, I should have a solid 420hp and 460ftlbs of torque. I say that because Edel claims 435hp and 487 torque with a 401cid (AMC's badboy) running 9.5:1 compression. My engine is 40 cubes smaller, so I knocked the hp and torque down a few ponies to be fair. However, I'll be running 10.75:1 comp, so I'll make some of that up. And, in all honesty, I'd be trilled with 420hp. It's going to be a street car/driver, so although the Edel cam is a little outdated, it really will work perfectly for what I intend to do. The thought of using a Offenhauser 2x4 intake has crossed my mind. That'd be awesome!
Oh, and I'll probably use a Tremec TKO500 with a Lakewood bellhousing.