The late hunting writer John H. Wootters, Jr. knew deer and he knew rifles. He told me that he felt the .35 Remington, like the 7X57mm Mauser and a few other rounds, just works better than its paper ballistics suggest. I think the same is true of the .45 Colt.
John killed a number of deer with the .35 and never found it lacking.
IF this rifle is in really nice shape and not rusted or too worn, I think it'd be a solid buy. I don't like lever actions, but it's one of the best.
I think I'd remove the scope and mount a Williams or Redfield receiver sight.
I think I'd keep the 9mm Colt. If it feeds good JHP ammo well, it's one of the stronger 9mm's and should last well. My son found even M882 9mm ammo pretty effective on men in Iraq, and the Federal HST or the Speer Gold Dot with 124 grain bullets is even better. If you want penetration, the FMJ 9mm rounds will penetrate until next payday. Even Elmer Keith respected 9mm penetration and cted a case where one was used na black bear.
I think a 9mm ball round in the face will reach a Bigfoot/Sasquatch brain. I'd rather use a .44 Magnum, but don't feel that you're helpless with a 9mm.
I think you should consider trading that old "reservation" .303 for a No.4 Enfield in really nice condition, and some are around. Many were sold here in recent years in the factory wrapping! I'd get some new Winchester 180 grain ammo and feel that the .303 was quite adequate for the role you mention.
But if you'd rather have a Marlin .35 in good condition, it's a killer within 200 yards. I think the Remington 200 grain SP will easily reach the vital zones on either Bigfoot or bear. The receiver sight is quick and okay for the range involved. Same for the receiver sight on the No. 4 Enfield.
I'd avoid light .35 bullets. But the basic 200 grain load made the caliber's reputation, which is good.
Frankly if I could have have just one rifle, it'd be a Winchester M-70 Featherweight Classic in .270 or .30-06, with a 2X-7X or slightly higher power scope. Leupold makes a 2.5x-8X that's an excellent idea.
If this rifle is beyond your means, the used Winchester M-70 of 1972 type may be available for a moderate price.