No such thing as a 78 SS CB550F. Last model year was 77.
Anyway, if I understand this correctly, you painted your in tank filter screen? Nice goin'!
If so, it's ruined. Be aware it incorporates a stand pipe for main fuel supply. The screen is intended to be withdrawn from the petcock hole. However, I would expect that the paint has glued the thing in there and it seems unlikely you'll salvage anything of it during removal. whatever you use to remove it, dril,l punch, pick scrape, etc., take care not to damage the tank bung inside or out.
Were I you, I'd replace the screen/standpipe assembly with a new or used good one. The lines are so short that each time you remove the tank, it will be a constant headache. And, if you leave the lines long they kink or trap air pockets.
But, that's just me. Most every one else on the forum owns stock in the filter companies. So, you just can't buy too many of them.

Cheers,