Sleeving engine block

Im considering having a 4 cylinder flat head block sleeved. Its already 60 over and although there is 80 over pistons available, I dont want to go that big and my block is numbers matching
I read were the very bottom of the block isn't bored to leave a shoulder for the sleeve to hit.
Is that standard procedure? Should a good shop be able to sleeve a block properly?
Has anyone had it done before