I am pretty sure the 59 degree blocks use the stepped bearings like the stock blocks.
That's not correct. The early48 deg "r" blocks and "r1a"blocks used stepped journals like a 59 block but with 48 degree lobe spacing. I have one and it uses std small block cam bearings. Call bullet or midway cams.
Why does this not surprise me ? Add that to the which oil pan and which crankshaft journal questions then. I am pretty sure that the MoPar UGL cams for the babbit blocks are all gone , but cores can be sourced elsewhere. But like everything else with these motors , bring your wallet.
