20 or 22" tires look much better. More seriously, what are your objectives? Handling, like the low look ect?

I've got my 70 E lowered a little (probably 3/4") with 1" T bars and stiff shocks. My 17" tires are on the short side with 25" diameter. I have a Hemi pan which is about 1" deeper than stock and a K frame mounted skid plate to protect the pan. The skid plate has earned its keep. I've had to touch up the paint on it at least twice after meaningful contact. It is sometimes driven with "spirit" on real midwest roads.