it can definitely be done. id say all you need is
Battery boxes #100908
HPI Idler Gear 44t/Shaft Set #100905 (converts your tranny to a single speed)
HPI Battery Box Mount/Cover Set #100909
Motor mount (three pieces)
20t pinion and 44t spur
2200kv motor
Blur esc
and chassis.

i think thats it. If you want you could also upgrade the diffs, and the diff cases. the flux has composite cases, and the bullet proof diffs that HPI just released are great. i just installed a set in my flux. you can also upgrade the shocks to the Aluminum or plastic big bores if you want the real deal flux but the 8 shock set up will work and save you money.