You wouldn’t have to route the Jagmaster, as it’s got the ‘pool’ routing in it. Most everything under the pickguard is open, it’d be easy to put in regular P-90s…just have to make/purchase a new pickguard to give you the space for the pickup. I’ve thought about putting in a Seymour Duncan Jazzmaster pickup, but I was worried about the hum. The Dream-90s from GFS is REALLY quiet, so I chose it.
I’m not a fan of spending a lot of money on electric guitars. You can do anything by changing the wiring and pickups. If I ever got the money to use, sure, I’d buy a Jazzmaster or an old SG…which ever I lusted after most that day. As it stands, I can’t…but I can make a guitar sound REALLY close to what I want. The only "stock" guitar I own is a Peavey T-60 and I’m modding it out now. Keeping the original wiring and pickup, but I routed out the body to lighten it, put a new back on, binding and am making a pickguard with only 1 pickup instead of 2. So, I will own nothing the way it came from the factory soon.