Is a 1 ton to 1/2 ton conversion possible without a new frame?

[fabnsmitty]

I have a friend thats gonna give me a 61 1 ton long bed truck as soon as he gets the motor and tranny out of it. What I was wonderin is if I can swap in a 73-87 1/2 ton front crossmember without too much drama? I know the middle of the frames are different heights but is the front and rear sections of the frames different too? I was just wonderin if I'd be better off just tryin to find a 1/2 ton frame? I can fab about anything I want but sometimes the amount of work isnt worth it.