If you're just trying for cosmetics, to make things look neater, why not some simple wire loom? They make it in black, chrome and varied colors. Most of it is split so you can feed the loom over the wires and cables without disconnecting anything. Check out the auto parts stores and especially any that deal in hot rod parts. I think you'll find what you're looking for. Here's one manufacturer. Drossbach - Corrugated Tubing Solutions and Wire Conduit > Home
As for filling holes you've already drilled with JB Weld, Jason is right on. It will add no strength and just cobble up the looks. Fiberglassing will add little to no strength to the frame in the way you intend to use it. Good luck, send us some pix of the finished project.