I think a modern hemi would be a smart swap. Even a bone stock 5.7 from a truck would be 390HP. If your desires are a nice driving car and not racing using as much factory electronics as you can would net you a great performing car that gets good MPG, great reliability, and you would still be able to roast the tires off no problem lol.

If you are starting from scratch modern power is a good option for any car really.