Well buying used, the 2.5 revos are, in general, a good bit cheaper than the 3.3. For what I would be using of the rolling chassis (3905 transmission swap), what would be different on these versions aside from swapping out the chassis itself?
The 3.3 uses the same length front and rear driveshafts, and the steering links are longer. Plus the tranny case is different for use of the rear brake kit, but that will not matter if you will use an emaxx tranny.