Lets talk a little about fiberglass repair. This will come in handy when you don't follow the ever important rule of measuring twice and cutting once. Unfortunately I did the opposite. In laying out the drain hole for the heater box I measured from the side of the hole on the original firewall to the centerline of the body we had established and failed to add half the hole to the centerline. Needless to say the heater box interfered with the brake pedal bracket. Ok, cut twice  and used the piece I cut out to fiberglass back in. Pretty straight foward. I ground down both sides of the firewall then used some Gorilla tape to back up the plug, smeared a thin coat

of resin on, a piece of fiberglass cloth and another coat of resin to cover it all up. Waited for that to set up, removed the tape then did the opposite side. Left it set overnight then ground it smooth. One thing I want to caution you on is grinding. WEAR A MASK. This stuff is nasty. Next I will show you how we layed out the cowl vent. Fiberglass and steel bodies do not have the same dimensions when it comes to thickness. Compensations have to be considered. You just can't trace a pattern and have everything fit. But then again maybe if I would have traced the drain hole I wouldn't be doing this post.