I would try to fix the TRI Z motor, maybe check for a used one on ebay, I'm not sure how much they go for. I had a TRI-Z with a YZ465 motor. All the mounts lined up but one top mount had to be cut off the frame. It had a massive extended swing arm, wheelie bar, and a bar in place of the shock. That thing was slow and gay and got smoked by my cousins 426EX. I sold it on ebay for like $400.
08 Outlaw 525s
07 CRF70
04 Harley FLHRCI
04 TRX90
03 XR650R
03 400EX- XR650R engine
02 XR100R
01 Banshee
00 XR50R
00 XR70R
99 PW50
99 JR50
96,95 Sportsman 400
95 Xplorer 400
94 Indy XLT
87 Trail Boss
86,86,86,86,86 Scrambler
86 TRX70 x2
85 ATC350X
85,84 ATC250R
85 Red Tecate
85 LT50 x2
84 XR500R
84,84,84,84,83,82,80,79 ATC70
82,79 XL500R
83 ALT50
79,78,77,77,76 XT/TT500
76,75,74 XL70
72,71,71,71 SL70
72 Harley FX
72,71,70,70,70,70,70 CT70H
72 SL100
70,69 Z50