From what I can find, the Marquis was a Japanese knock-off, most likey made by Teisco, so it's not like it would have historic value (but it does have personal value for you). So if it were me I wouldn't hesitate to mod the guitar to make it more useful to you. If you play it more- that's better, right?
I have a Jay Turser 335 knock-off that I call my "Mule" (in true Jerry spirit I put a mule sticker on it). It was the first guitar I started "messing with"- pickups, electronic upgrade, coil cut, brass nut, etc. It sounded surprisingly good for a cheap Japanese copy- and it sounds even better now. Fishing controls through the f-holes is do-able, but a hassle (use the string trick). I was really temped to cut a hole in the back, I think I would next time.
"Do not write so that you can be understood, write so that you cannot be misunderstood." -Epictetus
First show: 8/16/69 (Woodstock)
Last show: 3/19/95 (Unbroken Chain breakout)
Member of the Four-Decade Club
Charter Member, President & CEO of OAD (Order of the Ancient Deadheads)