Swing arm is from a 2002-ish Marin with the TALA system. Should be a direct fit to a JW2 or PRST-1. 29” in a PRST frame would take some engineering though, 27.5” barely fits!
Definitely confused by that front end, Whyte plus fours with telescoping legs? The mechanical origami that defines the kinematics on that set-up give me a headache.
Also, unless materials tech has moved on, I didn’t think it was possible to weld carbon fibre to 6061 aluminium, how on earth did you get that front fork to work?