Fuel tank replacement options opinions needed

[phatdaddy]

I'd take a 35 gallon drum or seven 5 gallon buckets full of water and set it in the stern where you think the fuel tank will go, and run the boat . You can run off of a portable 6 gallon while checking.
Gas 5o x 6 = 300lbs
Water 35 x 8,25 = 289lbs

This will give you some idea of how it will impact the performance running and sitting.