motor mounts are needed for big block power and Qoncepts, new era and traxxas make some. as for big block power, seems wasp .26, wasp .28, sirio .23 are the main contenders with the os .18tm being most popular drop-in replacement. the 18tm is said to be making 1.6hp but in reality closer to 1.9-2.0!
personally for bashingl when i need a new engine, wasp .26 it is for the power and torque it has. speed is nice, but really, when do you get the chance to get the revo up to 40+mph, not often unless your on the road or big land.
Qoncepts kit is said to keep the engine the lowest and is pretty complete.
4hp in a 9.4lb truck should make it really get-up-and-go.