Considering a 5.9 EFI swap into 68 Val -833 O/D car

Any one else have any input on either of these questions? Please tell me about what you have been able to achieve or what you would do differently. I'd really like to hear about it. Thanks

-Can a stock, reflashed PCM handle the duties of controlling a 375-400 horse motor effectively and efficiently? (thinking to go the "Hotwire" harness route)

-What would I have to do to my stock 5.9 motor to get it there? Would cam, headers, injectors and throttle body get it there? Or would I have to get into the mill and raise compression via pistons/stroker/decking, etc.?

Thanks for any thoughts from those of you who have done it!

CE