Maguras are a lot better than v brakes, though they aren’t as good as discs, especially in the wet. I happily ran Magura brakes on the rear of a non-disc frame for years, but would always want a disc up front.
Main draw-back with maguras is that if you ride in the wet then you’ll have to adjust the brakes every ride and they can be a bit of a faf sometimes. Make sure if you go down that route that you get quick release ones that have the pad wear adjusters built in.
Personally, I’d replace forks, discs and wheel, second hand if on a budget. There are a few forks out there that can be lowered with internal spacers down to 100mm, eg RS Rebas, SIDs. Fox do a few 100mm forks too I think. Some RS U-Turn forks can be wound down to 95mm eg Pike Coils, or Sektors. So I think you have a few options for forks.