Do a cranking compression test and a leak down check before you tear into it, that’ll tell you if that stuck float washed a ring or rings are good. If good, check the valve springs to see if all the viton seals are in place. Could have pulled an intake valve seal up off the guide. It could also be pulling oil up around an intake valley stud. Those are open to the port on those heads. Also check the plugs that block off the old nitrous nozzles. Maybe one got loose. Also could just still be oil in the exhaust that hasn’t burned out yet from before the intake gasket repair.
Short of a crack through the threads, I’ve never seen this being an issue with or without washers on plugs. Trying what hangnOout suggests would rule that out.
Check the intake face angle with no gaskets on. You may have to use ultra-grey on the superformance gaskets or those compressible moroso gaskets or mill intake as worse case scenario.
It definitely looks like it’s pulling oil from there. It looks as though the manifold is contacting the head at the top more so than at the bottom allowing oil in.
