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I started with stripper in the morning and had my car stipped by late afternoon, other than the doors which I did the next day. Piece of cake. I've actually stripped several cars, including steel-bodied cars. I worked for a guy that used to restore corvettes. We never had any paint problems due to stripper. First off, you've got to take it in sections and move from one to the other. Neutralize each section after you are finished. The GM black primer is not easy to remove, and, really, there is no need to remove it if you don't want to. I took mine downn to the GM black and then DA'd it down after that with fine sandpaper. What a lot of guys do, you have it down to the GM black, you take a scotch-brite pad and scuff it with the pad and stripper to remove any paint areas that didn't come off with the normal stripper process. Then use another scotch-brite pad with water and a hose and neutralize it.
I started with Capt'n Lee's stripper. It worked 'ok' but the spray bottle application was a waste of time and took forever. It worked ok in the door jambs which didn't have as much paint though. I switched to a wide brush out of a plastic container and that worked better ...but not great. I switched to Kleen Strip (Fiberglass-safe) stripper and that worked great! Seems more potent. My car had like 12 coats of primer/paint/clear and what not from years of being sprayed and sprayed again. Some thick areas I had to let sit for a couple hrs.
The trick after the car is thoroughly cleaned and washed off is to let it sit for a couple weeks to dry out. Then prime and do your bodywork over the primer (since polyester filler won't stick to SMC).
Good luck. Oh, and before you make the mistake, NEVER, EVER use a wax and grease remover on the bare fiberglass. It'll 'wick' up the W&GR and you'll have a heck of a time getting it off. Some rookies make this sad mistake.