His motor is 2900kv

6s * 2900 = 64 380RPM

Way too much. Motor is good for max 60 000. I would never recommend that setup.

Find a hull around 40" and let us know. Most of these hulls you are looking at take 1/4 of that large budget.

You could get away with running a
NEU 1527
8s or 10s LiPo
HV hydra 180

That would be less than $1500.

Ryan