Are you sure the shim you're asking about isn't really a dowel pin retainer or a bolt lock with tabs that bend up along side a wrench flat of each bolt?
He may be thinking of one of these. Helps spread the load for the flywheel bolts. This one is for a BBF.
I have the wire through type bolts , but I also have a shim that slides over the dowl pins and the four bolts go through it to the crank
It will not look just like the pic for the BBF. The dowel pins will be spaced in between the pattern for the bolts. It really just acts like a washer ,,,and it retains the dowels from coming out. Tommy