I have sanded my 70 Corvette down to bare fiberglass with 80 grit. I am going to use SPI epoxy primer, but I'm going to be busy with other things for the next two or three weekends, at best. When I get ready to prime, do I have to scuff/sand it again? Being fiberglass, there's no surface rust worry like with most cars. So when I'm ready, can I just clean it and shoot?