Pontiacs make great motors for trucks, but the parts to put them together are extremely limited. The main reason they are overlooked is because they will not simply bolt in. The problem lies with the bellhousing. Our trucks used the bellhousing to secure the engine. The bellhousing is the rear mounting point of our engines. I'm not sure if you can find a pontiac bellhousing that will bolt to your crossmember other than the 55-59 gmc v8 bellhousings. That would limit you to using a 55-60 motor. Of course you could always fabricate new mounts.
PM me if you need an alluminum bellhousing that will bolt up to the poncho and the sm420. As stated above more fabrication will be needed to make this bellhousing work.
I have a 59 pontiac 389 that has been bored and stroked to 447 inches in my 59 gmc, but the engine itself was a bolt in swap for the 336 gmc v8 that was in there.
