Rob,
Clouser's book on flies has a nice formula for poppers it starts with his E-Z pop but it also works on Lefty's Bug. I built my Lefty Bugs by eye based on what looked right for me. Surprisingly they fit Clouser's formula. Assuming you are using a foam cllinder, the diameter of the cylinder should be equal to the gap of the hook. The foam body should be equal to 1/2 of the shank length of the hook. The hooks I use with 1/2" diameter foam cylinders come from an assortment I got from Herter's about 40-50 Years ago. The shank is long enough that 1/2 of a stock 1.5 inch cylinder (3/4 inches) works. I bought some of those Mustads because they are said to go with Blockheads. In my eye they look small though they would work with Clouser's formula.
I will not comment on color. Buck sez, "The priorities in presentation are depth, speed, size, color, action."