Bill,
By not undercutting the 1/2" mount under the tank, you will lose some tank adjustment, unless you had 1/4" pads under the engine. I still like the larger mounts for the larger ngines. .60 & up.
Like I said elsewhere, the 1/8" engine pad and with the 1/8" undercut under the tank, is the perfect set up using a Sullivan tank with the PA.61, etc.
TY,
What's happening with your "Sleekster"?