Re: 7.3 or 6.0
i would go with the 7.3 based on the info you gave above it is stock....(wich means they probly didnt use it to hotrod around in..... for under a grand you should be able to put guages and a 6 pos chip on it with custom tunes and be over 300rwhp wich should be plenty i would think....unless you trying to make a race truck out of it.
2000 f250 ECSB Dually 4.10s 305/70/16, 4x4 7.3 zf6 200k miles
Php hydra chip PHP tuned! 4" exhaust, stock turbo(ww2, turbomaster wastage actuator, gutted ebpv), FRX, 160/30 sticks SB 1939-CB single clutch, home brew water setup for when i'm pulling hay through the mountains.