aux overdrive box

[gunracer1]

has any one messed with a brownie type box, running it backward as a 2 to 1 overdrive unit. or may be taking the gear portion of a np203 and running it as a overdrive unit instead of a underdrive unit? the brownie boxes are usually 1 to 1, 1 to 2 or a .20 under or over drive. the np203 is a 1 to 1 or a 1 to 1.96 to one ratio. both of these boxes are cast iron and heavy duty. am i crazy looking at these as options?