So I recently read the Retro Phaze RPG and the Final Fantasy d6 RPG, and I have to say, I have d6s on the brain.
Pulpwood! was originally going to use a d20 to resolve all its actions. However, I feel the humble d6 may be a better choice. They are easier to find, they are versatile, and outside of damage rolls, very few games feature them as the main dice for task resolution.
I generally find Retro Phaze's resolution mechanic more favorable, so I may just go the simple 1d6 resolution route.
I would need to reformat a lot of abilities for the various classes, but I don't think it would require too much work. I may also have to reformat how classes are in terms of skill points and possibly HD, but this is all up in the air right now