Either 5% or 10% nitro and 20%-22% oil. Mine likes Sig 5% - 22% 1/2 and 1/2.
Expect the Webra in stock trim to want to run fast, and I do not believe it will 4-2 with the stock set up. I have a Webra 28 (the same one Bob Hunt had at first in his published Tucker Special) and a 32. Both had had a *little* change to the timing, and a hemi job done to the head.
The Smoothie is relatively small, and the Webra will need a very low pitch prop to keep the lap times down. The Webra is pretty strong, and that combo will not load it much at all.
Bill <><