1st thing to mention is discs front and rear on a 26" isnt very good, the front is fine but a rear doesn't tend to hold well enough. I wouldn't dismiss maguras that quickly if I were you, maybe get a decent v setup on the front and a new hs11 from tartybikes for the rear, grind the rear wheel and get some decent pads. That should be a good enough starting point for you but I think you may struggle with a few bits on that bike, maybe pick up a 2nd hand frame off here to swap everything onto when you feel a bit more confident.