I went through and did a rough cost estimate for everything required for a 6.1 conversion and it came out to be around $10k including spending $3500 for a complete 6.1 hemi from LKQ wrecking yards. Don't buy a wrecked car because you will only use the complete engine that's it. Everything else will come from other sources like your transmission of choice (727, 833, Tremec 5 speed, 518, etc), custom or modified gas tank, fuel line, wiring harness, computer, engine mounts, headers, sensors, etc. There was a beautiful write up on Moparts that a covered the conversion on a white 71 340 cuda that went step by step and included all of the parts required, the part numbers, the sources and the prices.