Any 1956-62 235 or 261 is a good candidate for the neoprene seal, and I prefer them.
The only issue one needs to be aware of is, on some blocks, and I have seen two, the seal groove in the block is not concentric to the main line. This will prevent the neoprene seal from being held tight against the crank in one area.
On engines like this the rope seal is the only way to go.
