I would definitely not do this. You can always go back to geared if you save all the parts, but you can never get the original paint back. It's not a super sought after Paramount, but it's still a Paramount and it'll bring money. You'll destroy the resale value if you powder coat it.

As long as you don't do dumb stuff like chop off the shift lever bosses or derailer hanger, I have no objection to converting it to FG/SS.