I currently own a 71 mach w/ a 302 that has performer carb, heads, cam, and intake.  I'm looking at a 5.0 HO roller rocker motor out of a 94 Thunderbird.  The only reason i want this motor is b/c i would like to replace my old block and rotating mass (crank, rods, pistons).  plus i've heard that a roller rocker motor has a few hundred more rpm's than a stock block. obviously this motor is fuel injected and i would put all of my current mods onto that new block.  the guy is asking 500.00 for it but i told him i would swap him a pair of 289 hi-po heads along with some 69 302 heads.  the new motor has 52000 miles.

how much do you think that this motor is really worth and is the roller rocker motor really a higher rpm motor and how many more rpm's?