Your compression is good, but the 2nd ring is an oil scraper, and the 3rd is a pair of finer oil scrapers. If the compression is ok, it may only need more time to seat the other rings. They can take more time to seat than the compression ring can. Henace my "types of mileage" question. I wouldn;t panic just yet.
Good ont he breather - I think it's wise to double check the intake fitment. No gasket - just clean it all up and lay it on the engine, then look for gaps. gaskets will seal small surface imperfections. they probably won't seal if things are not "right". I know you checked with an angle gage - I would check it by trying to lay it on it.