I think the most expensive thing with the new hemi is initially getting it in the car, oil pan, headers, intake (EFI or carb are very expensive unless a stock one can get it done for you)... Heads can be had cheap as in $500 for used eagles that flow 330 CFM OOTB, stock rockers seem to take some abuse, blocks are good for anything most would do, stroker kits are only a tad more than a forged LA kit, cams are a simple re-grind away from big performance.

Once you get it in and running you can turn up the wick pretty easily/cheaply.

An off the shelf early 5.7 can be had around $1000-$2000 depdngin on seller and miles. Get the eagle top end (intake and heads) later for 12 to 1 compression that will run on pump gas and a cam regrind and the sky is the limit with a #2800lb ride. Just know going in you got to spend some $$$ to get it actually in and running.

I don't see how someone could replicate your engine for $7500 without far above average home porting and some un-realistic deal on an R3 block. Your at $6000 for pro ported heads and R3 then add rotating stuff, intake, machine work, valve train... for $1500?