There was a pretty spiffy Fowler design published in (I think) the July '86 issue of MA, where the model was a CL P-38 incorporating Fowler flaps.

AMA Plans Service can cough up a copy for a reasonable fee, and of course you might need to scale the plan up a bit.

If Small Parts doesn't have what you need, try [link=http://www.sdp-si.com/]Stock Drive Components[/link] or of course McMaster-Carr.