I guess my last opinion on the non-running boat would be a bit different than Jim's. If:
1. The non-running boat is priced to where a good mechanic can be paid to repair it and you are still at, or below, actual resale value.
2. All of the things not in working order check out okay by a reputable surveyor.
And detune the 900HP. Depending on how the HP is achieved, (boost, compression, rpm, etc.), you are looking at fuel issues almost everywhere on the water and rebuilds way too often for most family runners.