Man, I've seen that before! I had a Triumph mechanic do some work on my first CB750K1 26 years ago, and he skimped on new gaskets by using a tube of silicon sealant instead. Anyway, some of that crap blocked off both oilways in my head, and fried the top end. I had to buy new cam, cam towers, rockers, 1st oversize pistons, rings, and rebore it.
You might not need the pistons etc, but my bike actually seized, and if I hadn't pulled the clutch in, it would have spat me down the highway!
All up, it cost me close to 1000 bucks just for the parts, (I did all the work myself with a very knowledgeable mate) using all new OEM parts, except for a mild Andrews cam which was much cheaper than OEM. Of course, that was before EBay, so now I could do it for less than half of that money.
Make sure you pull the oil pump and screen out and clean it right out, and flush some gas or diesel through the cases to ensure there are no metal particles hiding in the bottom end or gearbox. once you've pulled the oil jets out of the head, blow out all the oilways with compressed air, and flush them if possible just to be sure. Cheers, Terry.