My understanding is that it already comes clearanced for stroker cranks. I'm looking into buying one myself for a forged 331 build and the local machine shop said that they wouldn't have to touch the block to build a stroker.(as far as clearancing goes)
You need to clearance them for the stroker. If this is a street car I highly recommend staying with the cast iron block.
Expect 500-600 in machine work inckuding balancing the rotating assembly. It should be taken to someone has done one of these blocks or atleast a Ford Racing block before.