Those 305 V6's are boat anchors. I have two. After having it awhile, I am starting to like it. It weighs 800 lbs! No real performance. Lots of torque. 4 1/4 bore!! Aluminum pistons. The most advanced engineered motor of it's day. (oiling, cooling and strength innovations). Lasts forever. Many parts are hard to find. I have some motor related parts. They are known as a big block. I have a 1960 GMC 1/2T 4x4 K1000 series, big window, custom cab, short fleet.(wideside)305A and 305E.
Yours has the torsion front end. It will have a 305D (stamped on passenger side, top front of block). Check for build sheet in seat springs; having one owner documents: money. If it has side trim: money. "GMC only" parts are more rare of course.
