The March 07 Street Rodder has an article on chopping a fiberglass body. It was on a 28/29 A tudor sedan, so it came straight down. You will have to do a little bit more to get yours, what with pie cuts and all. If you grind it correctly, the resin and mat or cloth secondary bond should be more than enough. Metal straps would be overkill IMHO. They could even cause you trouble down the road with corrosion and/or expansion/contraction issues.
Glass is good and bad. You can be as careful as you want. Chances are you are going to get resin and glass stuck to you somewhere. And, you will probably itch like crazy for a while. But you can make some sweet stuff with it. Just mix it correctly, toss it when it starts to kick instead of trying to save it, make sure you saturate the cloth or mat thoroughly, work out all your air bubbles, and make sure your secondary bonds have a good "bite" in the old work.