Looking to buy/build 500-600 fwhp 360

I was at a car show this summer and Im talking to a guy with a 70 Olds with a 454 Chevy( yes I know) hes telling me it has "800 horsepower" and it might have actually had it ,it looked tubbed and roll caged but street legal...i walked away and thought to myself "hes as old as my dad (about 75) what the hell does he need 800 horse on the street for?" LOL! these old guys just buy these cars turn key ready...they aren't wrenching or building anymore, I figured might have been what he wanted when he got back from Nam...