I've gone from an iron head 440 in my 70 cuda to a gen3 hemi. Bought the hemi as a core from the moparts sale section. Turned out it was a 7.0 crate motor. I had to replace the pistons, line hone the block, grind the crank and resize the rods and replace one intake rocker shaft and rockers due to a spun main bearing on #4. It has ported (unknown who did them other than it was cnc machined) 6.1 heads and I added in rocker shaft supports and locking spacers. Going to start off with the crate motor cam and maybe switch it later depending on how it runs. My car is setup for autocross/road racing so I'm not going for max power, but the weight reduction and extra power over the 440 is a plus. I'm running the 6.1 intake using Megasquirt for engine control. Currently hooked up to a 518 trans, but planning to switch that out for either a TKO/Passon 855 or T56 next year.