Most rod bearings have their specifications printed or engraved on them, so take a close look at the ones you removed. Once you have the model number, you can search for it online or visit a local bearing shop—they should be able to help you find the exact replacement.
it seems that Schaeffler's catalog actually lists individual needle rollers as standalone products. It might be worth checking their catalog to see if they have the exact size you need.
Wow, that sounds like a serious issue with the HST and the roller bearing. When you say the roller bearing is half missing, do you mean that parts of it have completely broken off, or is it just severely worn down?