I have a CMC body, bought, like you, in 1993!! and like you, I only got about 60% of what I ordered (although more stuff came after I took them to court).
I personally haven't seen any "under dash covers" although I had thought of making one up (custom) some time in the future to make that area much cleaner. IMHO, I would get some heavy-weight postor board and make up a template to cover the entire area to fit just so, then transfer that to either a sheet of aluminum or PVC to fit in the area AND make it easily removeable, then mount the whole thing with spring loaded, quarter-turn fasteners.
As for a radio mount, the guys in Best Buys' automotive installation department have a "generic" radio mount for under the dash which might be just the thing for you........check them out! You will have to either paint it (it's black PVC) or cover it with vinyl upholstery material, but that wouldn't be hard. You will, however, have to figure out a way to securely mount it up under the dash........
For my door panels, I used an inexpensive, Home Depot paneling (1/8" - 3/32" thick, I believe). It is flexible enough to bend to the contours of the door (it's curved in two dimensions). Over that I glued (3m-90 upholstery adhesive) 3/16" thick closed-cell foam padding (which looks suspiciously like anti-static packing material for computer boards in a roll of 40" wide pink foam material, but Pergo floor padding from Home Depot would work as well) and then carefully glued the vinyl material over that (using CMC's instructions), giving a nicely padded panel. I have no exposed fasteners on the doors, as I used blind clips as are used on American car door panels.
I fought the suggestion to install kick panels and now I think I should have gone the kick panel route, if for nothing else than for lower front speakers. However, if you don't go the kick panel route, you can simply glue the carpet material right onto the inner fender walls.
Under the carpeting (everywhere) I installed Home Depot rubber shop floor padding. It comes on rolls like a carpet (like 60" wide or more), is a little over 3/8" thick, cuts very easily with a utility knife and does a nice job of padding your floor areas (and cutting down on noise). You can easily make paper templates for fitting and cutting and can then glue it down with 3M or leave it loose (I glued mine). The carpeting glues to it nicely, too, but I left mine loose and simply attached snaps at the rear of the carpet peices.
My engine compartment already had the side panels and firewall installed, so all I had to make up were the rear, upper horizontal panel and the horse shoe shaped panel around the engine (mine are sheetmetal) and those I did from paper templates.
So I guess the short answer is that they are all custom panels, but they are all reasonably easy to do if you're resourceful.
Post if you need help.............gn