possible engine swap?

[tomogchi]

Good evening,

I have recently thought of something. My 5.7 liter motor isnt as great as the day it came off of the production line, nor is it like it was after the rebuild. I found a 5.7 liter vortec motor, complete with ecm/wiring harness/tranny, everything for $800. the motor only has 40,000 miles on it, with the paper to prove it.
Would it really make that much of a performance leap if i put the 5.7 liter vortec in there? Would i have to beef up the supsenion or rearend or anything?
I thought about puttin rear discs on the roadmaster if i ever do an engine swap, but i dont see kits, nor do i exactly understand how it would work.

Thanks,
Bill