Nice looking frame/bike you've got yourself there.
I know you are constrained by the non-disc fork and swingarm so v-brakes it is, but I've built 4 full-sus Marins for my 2 daughters, my wife and myself. My youngest's Mount Vision has grown with her from a 13.5 to 15.5 to now a 17.5 by just changing the front triangle and transfering all the bits including Rockshox, Hope wheels/discs. Oldest daughter has a Wolf Ridge, Hope wheels/discs, RST fork. My wife's Wild Cat Trail started off with the swingarm that has Marin's idiotic non-post mount, non-IS caliper mount so changed swingarm to one with a proper IS disc mount from another Wolf Ridge frame I had bought. Her's has an RST fork, Formula wheels and Shimano disc brakes. All decent bikes built on the cheap over the years but way, way better than Halfrauds type crap.
As you mentioned changing fork maybe what I did with the other Wolf Ridge frame and swingarm off the Wild Cat Trail might be of interest, give you ideas in case further upgradeitus takes hold.
The swingarms on these frames are interchangeable as long as you use the correct length shock for the front triangle. Realised the Wild Cat Trail swingarm was 30mm longer than Wolf Ridge original which is added on to length near drop-out. With correct length shock this gives approx 120mm of travel, a good bit more than travel on period type fork. Bought a Marzocchi Z1 Wedge with 130mm travel, built it up with Hope hubbed wheels and Hope disc brakes, 3x8 drivetrain, wide-ish bars, shorter stem. Made adaptor for problematic disc mount on swingarm to get around the daft mount. Felt weird at first after riding my F800 Cannondale hardtail with 100mm Lefty, but got used to it and it felt good on harder downhill stuff that the Cannondale, and me, couldn't cope with. That was about 3 years ago, till last year when I got a new, modern geometry hardtail with 150mm fork, so stopped using Marin almost entirely. Fast forward to earlier this year when through boredom needed a bike to build/upgrade so Wolf Ridge was the focus.
Found a Hope hubbed wheel with 15mm axle and a Fox 140mm travel, 15mm axle fork that went with it off a guy in Edinburgh who is on Retrobike. Changed drivetrain to 1x10 with Shimano 10 speed shifter and XT rear mech with 11-50 cassette, single ring RaceFace crankset. The front mech on these Marins is a pain trying to fit and adjust it with swingarm always seeming to be in way so why not just get rid off it? Replaced brakes with new Shimano 4-pot disc brakes. Even wider bars and even shorter stem than before plus Maxxis 2.4 front and 2.3 rear tyres to complete rebuild.
The longer fork has changed the head-angle so bike handles a wee bit more like a modern bike, think it is around 67/68 degrees compared to my modern hardtail which is 65 degrees, but it will never be quite like a modern bike. The frames are capable enough and can cope with longer travel, there will be guys who'll say it can't cope and it'll break, I disagree. I'm never, at my age, going to be throwing it down steep DHs at warp speed nor would I be if younger, you really need a proper modern bike for that.