Gotta back up the reman idea if you don;t have the space and tools to do it. Otherwise the parts can be had through Kanter or NAPA to rebuild it. I recently threw a re-main kit from Napa in my 305E but had to get the new timing chain and gears from Kanter. Parts have run me about $500. That includes a carb rebuild kit, cap, rotor, coil, condensor, points, plugs, wires, and fluids and filters. A reman 305E motor was about $1600 from Advance Auto Parts.
My timing chain was stretched more than I wanted to keep. I didn;t realize how bad until I put the new one on. Be sure to replace it if you rebuild.
As far as swapping to a V8, base it on what you do with the truck and how original you want it.
