Unequal length crank arms won't do it. In order to accommodate the shorter leg, the longer leg will be sub-optimal. And vice-versa.

TA pedals had removable cage plates that could be had in different heights to accommodate unequal leg lengths. They've been out of production for years, and while they do show up, they tend to be pretty expensive (they're darned nice pedals, regardless of whether you need the orthopedic cage plates.

Specialites T.A. - pedals & cleats

If you use clipless pedals, you could fabricate a spacer to go under the cleat for the shorter leg. Sounds like a job for a 3-d printer, as [MENTION=520543]jay4usc[/MENTION] suggested above.