For a BMS crank it really depends on the race series that the engine was designed for. 2.66 ( which I have never held before) all the way up to 3.625. In a stage 2 motor the 2 most common sizes found were 3.59 and 3.625 to put you in the 274cu inch ballpark. The 3.59 motors had the 4.020 bore. Do a quick measure on your bore or look for more numbers hand stamped on the crank. I still have 2 raw BMS forgings that can be machined down.