I know disposable income is often the driving force when deciding to try restoring vs replacing parts. As for me, I'd focus on either finding used fillers or buying repro ones. Either way, they aren't that expensive vs the time and cost of supplies to fiberglass repair your existing ones...and, who knows how well they'll hold up, anyway. The nose, on the other hand, is something you can't easily and cheaply replace unless you know of a good donor locally...so, you're faced with the task of restoring what you have. I believe 3M makes a urethane body filler that might work. Maybe Google their Automotive Products site for info.