Upon further review- Seems the Briggs/Yellow/Blue issue is as much about diameter as thread pitch. I pulled the trashed Briggs off the shelf and compared the oil fill caps of it and my Blue motor. While the threads appear to be the same, the Briggs cap is a CH bigger. The Blue cap will fit the Briggs (being slightly smaller) while the Briggs cap is too big to start in the Blue motor. Don't have access to a Yellow to check it.
The main reason I asked is as the Kart motor is stock (being as it's for the Grandkids) it didn't look like there would be much clearance between the muffler and the pulse line if the fitting was in the valve cover. In a "Duh" moment, it occurred to me that a right angle fitting will take care of that, eliminate the potential oiling problem that might be caused by using the oil hole, and also be better as it will be closer to the pump.
All this is brought about by not having anywhere near the chain adjustment I need due to the clone fuel tank hitting the chassis seat frame and limiting how much I can move it when using the original motor mounting slots. I added a ProMod adapter which helped, but only a little bit. If a bud comes through with a floor tank and pulse pump the problem will be solved as I can go back to the stock engine slots in the frame and with no stock tank chain adjustment will be OK.
I think I'm on the right path, if so I'll post pics of the "Updated Lo-Buck Special" once I get it straightened out.
Thanks for the opinion, all.