big vs small block 2001

what advise on a 454 barefoot 2001 given that gas costs $8.20 per gallon in ireland.
Is there much of a penalty in consumption. Were only talking 30 hrs per year. any comments!

10-15 gph on newer mercruiser engines , thats at wide open throttle but if youre adding sacks and people id imagine you wouldnt be to far off of that estimate..especially given its an older carbuerated engine, could be expensive.

swap the fuel system out to propane, the powerloss should be negligible with that motor.

for only 30hrs a season I'd make sure I have fun at the gas station too!!!!