I agree with the efi and 500 is heaps
My xb runs a 393 with efi and makes a lazy 400 @ the wheels which is probly 550 at the engine maybe more and it's under the bonnet and a steeter not really a racer
Engine us getting on in age too
I just think 500 could be 600 for the same bucks and be just as streetable
Just my 2cents worth
Steve