Freewheel sets.
Picked up a Mongoose Stat 29 for nearly free.
Like the design, I'm not a fan of the typical Big Box Bike 3x7 21 speed for a 29er.
So since its a build and sorta budget minded. I have to buy new shifters anyway.
Three choices. Freewheel sets
Sunrace 8 Speed mega range rear, 13-34t
DNP Epoch 9 speed 11-32t
SunRace 10 speed 11-34t
Changing out the BB too and going with 42T-32T-22T