First off, welcome. As far as the additional HP of the 2BBL over the over the 4BBL versions of the engines in addition to the areas you mentioned, the 4BBL engines also often benefited from higher compression and a hotter cam.

The Ford FE engine series (which includes the 352) CAN be a pricey engine to build properly. If you eventually plan on building a bigger FE to eventually transplant into the truck and basically plan on using the 352 as practice, I would suggest you buy the truck that has the most solid engine in to begin with.

I can be well worth having a professional mechanic go ever the drive train, checking things like oil pressure, cooling and compression. Throwing speed parts on a tired old engine will be an exercise in frutility.

The external parts you buy can be transferred to the bigger engine when it comes time to build it……although you will probably want to upsize what ever cam you put in the 352.