Hello Al-Nice gun; thank you for showing it, here. Your gun has a nice maple stock and good length. The triggerguard appears to be Western PA, as it has the WPA filed chevron on the bow, (as you suggested). The lock looks to be what you have already divulged. that is, a Ketland export lock. Altogether, it looks to me like your gun could have been made in PA somewhere, or if elsewehere, the maker perhaps borrowed some parts from various places. However, even though the architecture would fit into several schools the T'guard puts it into central or western somewhere, in my opinion. Thanks again for bringing it here.
Dick