Hi De;
I have done exactly that, and have emails out to several companies, but have gotten no response just yet. Phone calls nay be better but hard to do at work during the day. I have even pinged a few down your way in Oklahoma, like Dusters and Sprayers Inc in Chickasaw. If you look up the Stearman PT-17 and engines used, there is quite a variance over the years. Plus I have seen R-670, R-680, W-670, almost like trying to decode a Waco! And then there are the different varieties within one displacement! But I imagine they tried for some commonality in parts and maybe used the same valve cover on all. Time will tel. I'll try calling some this weekend.
Type at you later,
Dan McEntee