New Power for 27 Tournament SeaCraft

[TBubrick]

Looking closely at the boat Todd has for sale. It has no power today, but an Armstrong bracket in place. The fuel tanks will hold a lot of fuel, about 380 gallons...and there is a 40 gallon fresh water tank to be installed. Also a double bow T-top.

My question is there a way to estimate performance of the various power choices? Recommendations have been from twin 200s, 225s, 250s and 300s. How might I get estimates of cruise speed and fuel burn?