Repair Machine Part to Casting Part

 From:  Anis
4017.1 
Hi....

I got a machine cast model in step format from my customer. To create core and cavity for the part I need to remove "machine area" then make it back to the original shape before "machine". Is there any suggestion to make it fast in MoI ? I have tried "delete" face but still need extra steps and manual tune up to get the final result. Image & 3dm below are for your reference...

Thanks...