I've overhauled a few OS FT160 twins, the bearings (5) are available from Boca Bearings. I buy the Hard Chrome version and use a 2RS ( rubber seals ) in the nose. The front cam bearing can be a challenge to remove. You'll need a high quality precision hex driver to remove the rod cap screws.

I recommend removing and measuring the bearings prior to ordering. Boca's site is not always correct when ordering by engine type/model.

I typically replace the rings with a pair of RMJ Machineworx/Bowman rings.