How about keeping the Nishiki hardtail frame and upgrading the wheels and suspension shock. Something like an older Manitou air suspension fork with a straight steerer at let's guess $400. Then find a decent carbon wheelset on AliExpress for another $450 or so. That leaves $150 for sundry items, maybe tubeless tires or improved brake calipers. Replace your outer ring with a bash guard. Anyway, it'd be a solid upgrade and likely better than you could do for a complete $1000 bike. Think about it.