Off the cuff, I suspect the frame is French made, simply marketed under the Pierce brand. You might do a search to see if the graphics and any logo, match what was used by the Pierce MC company you know, or not. I also suspect the drive train is original, or at least period correct for the frame.
You can learn plenty by measuring the stem diameter above the headset, and/or checking the fork or bottom bracket threads.
In any case, this can be a nice project, and as I said you should strive to keep as much as possible while you clean it up (restore would imply more than what I have in mind).
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