361 engine specs

Big blocks came in 2 flavors, B and RB. The B engines used a 3.38" stroke, had their own main journal size and rod length. The RBs used a 3.75" stroke, had larger main journals and longer rods. They also had a 1" taller deck to accomodate the longer rods and increased stroke. The B engines were produced in 350, 361, 383, and 400 cubic inch displacements. The RB engines were produced in 383, 413, 426, and 440 cubic inch displacements. The 350 B and 383 RB shared the same bore size as did the 361 B and 413 RB, 383 B and 426 RB. The 400 B came with its own specific bore size (4.38") but shared the same crank, deck height, and rod dimensions as the other B engines. The 440 RB also had its own specific bore size (4.32") but shared crank, deck height, and rod dimensions with the other RBs. The 350 B and 383 RB didn't last long, being phased out by 1960 so I doubt you will see very many of them. I think their bore size was 4.06". The 361 B and 413 RB had a 4.125" bore while the 383 B and 426 RB came in at 4.25" bore size.
Now to make it work. To rebuild a 350, 361, 383, or 400 B all you need to find are the specs for a B engine regardless of displacement. Any RB can be rebuilt from any RB specs. The only thing that will possibly change is the piston to wall clearance and the ring end gaps and those specs will come with the pistons and/or rings. Hope this helps.