I had a set of mediums holding a 44mm scope on a standard Weaver 1pc base on a LA and with 20MOA raising the rear and it just barely cleared a Varmint barrel. I am willing to bet if you are going to use a 20MOA rail you will need the High rings.

Just curious, why go with a 20MOA rail when the Sig Zee rings can easily give you the 20MOA with the offset inserts?