Not sure about your math.
270 crank offset ground for a 4.375" stroke
The original 270 stroke is 4.00"
The 270 pin is 2.3125" (nominal), reduced @ maximum eccentricity to 2.125" removes .1875", which moves the journal centerline outboard by .09375".
The new stroke is 4.1875", not 4.375".
