best you could do ahead of time if no one has one (or knows that dimention which would prob be diff from yours) would be to take the nominal #'s for the block deck 10.745") minus 1.875" (1/2 the stock stroke) minus the rod C to C (6.768" iirc) minus the piston compression height: (lookup that dimention or measure w your 1-2" mike from the top of the pin bore (it's curved so use a 3/8 etc rod under the mike anvil) to the top deck then subtract the 3/8" then add .545" (1/2 of pin dia) to get the piston compression height.