BarclayG,
I was linked to this subject from a another thread...Drew may be correct about it being a GI piece, although when I first looked at your gun and saw the ivory grip cap, I thought G&R Tackle...G&R had several engravers on board and two outside stock makers...It may be worth while to email Bill Mains with a photo to see if this was a G&R made gun...The ducks on the bottom kinda look like the early work of Mains.
Mains has a website, perhaps he would recognize it as his work or the work of Ray Swan. see
http://www.billmainsengraver.com/About-Bill-Mains.htmlBesides the engraving, the gun was either restocked or at the very least re-checkered which suggestes more than one skilled craftsman...and that checkering is the work a highly accomplished checkerer.
Also, I would like to apologize for Ted3000 and his vicious comment about it being a "chromed turd". He feels the need to poo-poo every every gun or post that isn't owned by someone he kisses up to. I'ts strange how the other readers find his sharp tongue socially acceptable, even when he insults a newbie. He has nothing constructive to offer, no knowledge of the gun in question, yet he was compelled to berate your gun. He did follow up with "nice gun" but too late, he had just opened the door to other mud slingers...
If it turns out that Drew's assessment is correct, then your on your way...If it looks like my GUESS may have possibility, you can email me and I will post a seven page history of G&R (with a link)
Just got off the phone...I'm printing photos of your Marlin...another Iroquois Arms Collector member is on his way to pick them up and drive them (40 mi each way) to the last surviving G&R owner to see if he recognizes it. Even if it is, he may not recognize it as hundreds of custom shotguns passed through his shop across the 60' and 70's. Either way, it's worth a try and I may have the answer later tonight.