That's a tough question. What are you trying to achieve? If you plan on replacing lids & fenders with fiberglass, I wouldn't cut until you actually get the parts you're going to replace them with.
If what you want is weight loss - start with the simple: undercoating, gobs of seam sealer, soundproofing behind the backpad, carpet, tar on the floorboards, pad in the engine compartment.
By your name, I assume you have a 75. Have you backdated your bumpers yet? There's big weight loss there, too.
-Rusty