The 4.3 is actually a 350 with 2 cylinders cut off. It has the same 4.0" bore and 3.48" stroke as the old small block 350. Because of this, there are a lot of performance parts that transfer over (inlcuding a lot of internal parts like rods, pistons, etc.)

If you are REALLY interested in a engine swap, look at the new GP GXP motor. It is the 5.3 truck motor, rated at 295HP and 315 lb/ft, and should be cheaper than a Northstar transplant.

wow, that will kill the Bonnie GXP.