All you have to do to the 5.7 is put in a mild cam,k&n cold air induction and new chip and you get a screaming 5.7 with 450+hp with no limit on rpm or speed, my Durango has a factory limiter on it at 5800 RPM and 110 MPH.
The 5.7 would make a great swap engine and if you added headers with a good exhaust systems your dream machine would be a screaming sleeper.
If I was not so fond of the 273 commando in my 66 Barracuda I would consider the swap myself and I may in the future.
Good luck and let us know how it works out.