i have a 4.3 5speed in my truck now…im going to a 350 with a 4speed mc1 with about 400hp and maybe a 150shot…should be fun…with your choice ive seen some badass 4.3 builds with aluminum blocks made and everything but for the power i see alot more potential outta the v8…plus you can always lighten up the front end to even out from the extra motor.