3) Also, i would like to amend my thoughts concerning 4.3 vs. 305 and 305's in general:
i was looking at the torque curves of both engines (that's what i do......) in the gm heritage section. While the 305 "only" makes about 5hp and 5lbs torque more than the 4.3 AT PEAK, it does it a a lower rpm AND it's torque curve is much flatter than the 4.3's.
So the 305 not only makes more power, it does it at a lower rpm, and more consistently in the lower and higher rpm ranges; The 4.3's power curve looks more like a mountaintop, while the 305's is more like a plateau.
i think the 305 would likely make a better towing engine. On the other hand, with the right gears, the 4.3 could do ok for towing, but still wouldn't be as fast as the 305.
i think the takeaway here might be-----don't just look at peak numbers, look at the entire power curve.
4) The 305's radiator hoses "should" plug right into the 4.3's radiator. This radiator could probably be adequate for a while if you're not towing/hauling. Personally, i would not run this way for too long and would get a v-8 radiator, but that's just me.
5) The 305 might run even better because of the 4.3's torque converter. Which trans do you have?
i will try to get a picture of the mounts this weekend, but might take a while since they are somewhere in the garage........