>
>None of my planes (except 9 1/2 @ 60 1/2 blocks) have what I consider to 
>be a close enough mouth (I keep my frogs flush with the mouth). I have 
>been wondering if I could just put a metal shim behind the (whole) blade?

I have done something like that with some of my woodies, most recently I
used coated paper (People magazine front cover I think, wonder what the
galoots of 2050 will make of that!) to shim a beautiful old rabbet. Works
great!

Go for it!

Philip

God First, 
Your neighbors as yourself.
All else is commentary.