Does anyone make a windage tray that will fit into a stock sbc oil pan for a pre 1980 engine?

A GM windage tray, z-28 style should fit.

Yup... but only if you get the right "stock" pan. They're not all the same, you know.

This is the one you want.

http://www.paceparts.com/product.asp?0=243&1=257&3=29