The carb is the same as the Warrior. So is the head, so a set of Warrior valves won't do anything. All the 350 based engines share the same top end. After running mine around the farm, I'd do an 11:1 Wiseco, .415 Mega, HD springs, exhaust, K&N, and leave the stock carb on it. I don't know if I'd go with a 39mm FCR on this bike or not. Honestly, anything that flows better, that is a direct bolt on would be nice. Providing it has an accel pump. I think the newer Wolverine 450 has a spigot mount carb, instead of flange mount like these have. I was given a spigot mount manifold that the guy had, so I think he got it for a newer Wolverine. May make a spigot mount carb work great. Possibly a 400ex carb? That you can install a QS3 accel pump cover on and tune the accel pump.
I don't know if you'll like the 25" tires, Ed. These suckers are geared really tall, and any increase in tire diameter will raise it even more. Right now it may feel snappy because the front driveshaft is out of it, making it a 2wd. But, trust me, once she's having to spin all 4 tires, you'll feel the power loss. The added power from mods will help, but all you're left with is a quad that feels nearly stock because all the added power will be used to turn the bigger meats with the tall gearing it has. The Wolverine uses the same height tires as our Fourtrax(es) and I've never EVER felt the need for a taller tire. Unless you're going mud bogging 24/7, stock size works really well.
Also, you may want to save up for a WARN 424 front drive shaft. It allows you to switch between 2wd and 4wd. Better mobility and less steering effort. They can be found on EBAY. Warn hasn't made them in some time, but, there is a company called Switch Out that is making them now. I'd love to get one for my dad's Fourtrax. It's like gaining 5hp when it doesn't have to power all 4 wheels!