Bigdoug,
Welcome aboard. We all love a challenge here when it comes to ID'ing a rifle, etc. If it is a 'wall of any stripe, some of us get all interested in a BIG hurry, 'cause that's what we like!
Anyhooo, the first thing to remember is that any alterations make the rifle that much harder to ID, but let's look at what you have. First, how is the trigger tang set up? Is it part of the receiver shell and not removable, or are there two screws, one on each side of the receiver that retain a separate piece that can slide out of the shell and be changed? If the former, it may well be Browning made, if the latter, it is most probably not. BTW, Winchesters did not have the roll mark on their top tang throughout the manufacturing run, and it is not at all unusual for those markings to have been polished off and or engraved over, either. The serial number and patent date on the lower tang are definitely right for it to be a Winchester, I don't know about those markings on a Browning, though.
Looking at the shape of the breechblock would also help. Is it scalloped down to sort of match the contour of the lowered sidewalls, or is it high like a high-wall and just rounded off a little on the back corners? Also, is the receiver totally flat on the sides (a type mistakenly called by some a "thick side") or does it flare at front and back where it meets the wood? Another aspect of the shape is in profile, does the rear of the receiver make a straight line down each side or does the wood make a little arch into the receiver? All of these, absent a picture, will help with the ID process. Regardless, figuring this all out will be an enjoyable exercise.
Regards,
Charlie Shaeff
aka Green Frog