like you have done all the checks necessary to ensure the parts were fitted correctly. Often they will only fit one way but there are occasions where a gasket could 'fit' upside down.
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Unlikely that running the engine would clear the blockage as normal oil pressure wouln't be high enough.
Did you put 'gasket seal' on the head tgasket it's self. Normally all you use if necessary (or at all) is a thin smear of light grease.
Did you have to scrape the old gasket off? it is this crud that, if you are not careful, blocks the oil chanels. These would be small holes (3-5 mm at most) in the block & head. The gasket sometimes has a aluminium 'seal' built in to the gasket around the hole.
Unfortunatly the only way to check them is to remove the head & blow out with a high pressure air line.
As I said, the shavings could be the camshaft bearings breaking up so you may need to remove it to check. A blue colour across part of the shell, scratches or missing pieces are signs of a bearing that has ran dry.
Bearings could be 'shells' or 'ball bearing' types, as I say I an not familiar with bikes as yet.
If the engine has ran for more than 10 seconds I'd expect oil to have been pumped up to the area. Depending on how long it ran for damage may be minor or major, it's hard to guess.
Anything that is normally oiled in use should be oiled on assembley with the relavant oil. Other parts (ie piston, upper cylinder etc.) wiped with an oily rag.
Other than what I have offered I can't suggest anything further to check. Prehaps someone with more speciffic bike knowledge could expand/correct anything I have said.
Remember, I was a car mechanic & while they are basically the same there are differences I am unaware of.
Hope I have been of some help.