Hi everyone, I hope someone can help as I am very undecided on this matter.  I am looking to build a new engine for my mid-late 80's suburban (I have an 84 1/2 ton now, but depending on if I decide to go with a BBC or a Stroker I may buy a new 3/4 ton w/ the 454 in it and TBI).

I am currently torn between building a powerful 383 and building a 454.  My biggest concern is Gas Mileage and Longevity.  I am highly concerned that a 454 will kill me at the pump.  I have heard you can build a 383 with the same performance as a BBC 454 but with extremely better mileage.  Money really isnt an issue as this will be my project truck that I plan on keeping forever.  I will be using the truck for towing a 24-28' Cuddy Boat and need the power to handle it and not bog at 35 mph up the canyon.

I have been told by 2 different machine shops that the 454 would be the way to go but I think they are going purely off power output and not any other factors.  I plan on adding MPFI on the finished product so hopefully that will help as well.  One machine shop also told me that the RPMS would be considerably higher on the 383 for the same power output as the 454 because of the need to run shorter connecting rods due to a lopyier crank.  

Any info on the matter would be appreciative.  Thanks in advance!    

due to the size of a mid eighty's Suburban,id definately go with a big block.any way you slice it,you are going to be paying at the pumps,due to the size and application of the vehicle.you should check out the GMPP crate motors available,or any other engine builder that mass produces crate motors,as they will steer you in the right direction.hope this helps.  

I would rather spin low rpm,s with the 454 than scream a 383 to make the torque you will need to happily move your 6000lb SUB. Dont count on fuel consumption being any better with the 383. Lots of big block torque is whats needed for that ride.