I'm not used to NC rust, I wish I had California rust but I'm real familiar with Pennsylvania rust, and it really stinks! Usually it means everthing below the door handles is gone or suspect, and there's no chemical alternative for repair- you need to weld.
Whoever sold you the West system did their job, they descibed their product and it's advantages. But looking at their website it looks like they're into non structural repairs. Patches on quarter panels, floorpans, even trunk floors would be great- as long as there's some metal to bond to you can create a solid non porus (read "not Bondo") surface that's plenty hard. No problem there, if you want to do that instead of weld in panels or patches that's OK.
But when you're talking about a structural component of a unibody vehicle you start to get into a different situation. The cowl and inner fenders are welded to the frame rails and T bar crossmember, and that does a couple things- first, holds up the front end and the power train, it keeps the body sguare so the doors close properly and the windshield doesn't break when you hit a pot hole, etc.. The engineers that designed it back in the day understood it all works together as a system. The epoxy is a different animal. Not only from an engineering perspective) different modulus of elasticity and tensile strengths, etc) but the epoxy gets harder than steel. That sounds good, but when you're trying to fix an existing structural defect there's already a problem. You can fill it with the magic epoxy and cover it with whatever you want, but it's still not doing the same job as the original. You might get it all back together and put a 318 in it and never have a problem. Put a bigger motor in it and horse it the body will flex. Steel remembers where it should be, the epoxy is going to either separate from the metal or crack, even with reinforcement in it. And God forbid you're in an accident.

Automotive epoxies have come a long way, I can remember when the first Fusor products came out. But they weren't then (and still aren't) used for structural components- you can't glue in a replacement frame rail. But just for kicks email the tech people at West and ask them if their product would be warrantied as a structural repair medium for a steel automobile. I can already guess what they'd tell you- No. Boats are a whole different breed of vehicle compared to an automobile, they're built with different materials for a reason. Even a fiberglass vehicle really isn't- maybe some exterior panels, but study the way a Vette is built and you'll find not only a full steel frame under it but a lot of steel supports in the body as well.

Not trying to just start an argument with you dude, it's a nice car and deserves to be saved. I'm glad you're working on it. If you can't weld the major stuff like that it wouldn't be hard to find someone that could. It's a lot more than proving a point that you can do it- welding a patch in that crack probably would have taken less than a half hour and probably cost way less than $50 from a welder. I have friends that would have done it for nothing. But unless you're planning on welding in subframe connectors I think you're going to have problems, and why waste the time and effort then have to do it over again in a year or two?