The "Cadillac 261" uses a standard 261 (or 235) crank and 292 connecting rods. The rod journal on the old engine is larger than the 292 so have your crank ground "off center" and it acts as a mini stroker. I can't remember the exact pistons used but they are from an older Cadillac V8 (like a 368 or something) and have just the right piston pin height to work. Depending on the over-bore it gives you around 285 to 288 cu in. Tom Langdon at the Stovebolt Engine Co. has all the pieces. If you go to the Gallery you will find a picture of my '50 pickup and the engine under Ron and Kim Plenders 1950 pickup.

1964 Chevrolet C-20 Fleetside, Otis
1950 Chevy 1/2-Ton, Kirby
1950 Chevy 1/2-Ton Shortbed, Walter