I know the new Hemis are kid of the go to modern engine to go with, but I think if I was going to go with a modern engine in ANY retro rod, it would be a chevy LS engine, hp to dollar cant be beat, super reliable, a ton of tech and parts support, and they are awesome.
Now I know people will say "its a mopar, use a dodge motor", but that wouldnt matter to me, I like chevy ls, lti, sbc, bbc, all good motors, and for your money just plain better. The only thing you can complain about is the name tag, and I just can not bring myself to be that shallow. I'd put a toyota engine in it if it made more sense to me a the time, I had a 5.7 tundra with the toyota super charger that would run all over a 6.1 hemi and when I got rid of the truck it had a hard 140K miles on it, I used to mat that thing 4-5 times a day, it was just that fun, lol...
BUT if you want fuel injection, then add it to an era correct motor, save yourself some trouble and probably some money..
Before I spent the money on a 6.1 hemi driveline (they are ******* expensive), I would get the 6 pack fi set up from f&b
https://www.youtube.com/watch?v=0fMlCgH5OFY with a decent 440 engine build. No cutting and chopping so if someone wants to bring the car back to original its not impossible and it looks bad ***..
Just my opinion we all have them...