hello emil and welcome to the forum. this is a great place to come and share your truck interests.i would give you my opinion about a choice of the motors you have available, but i am worried about what you concider to be a medium size boat,and what do you mean by occasionally towing it. the best all around motor might just be the original straight six. after all ,it has been around and working in the truck since 1959, if it is the original engine. the v8s are more powerful, and finding parts for them is no problem,but some swaps from 6-8 can be tricky. i agonized at great length about this same choice. i have a 1955 first series truck and a few sbc engines around to put in, but i went with the 235 straight six for now. it is basically stock with new rings bearings and gaskets, and a home made dual carb intake with to two rochester model b carbs. it ranks an 11 on the 10 cool chart. a t5 tranny and the stock rear finish off the drive line. so let us know more about the boat thing and we can go from there .i am sure that others on the forum will chime in also. good luck.

our garage is a non-profit organization