This is a poser. The thing that throws me is the spinner. That looks like a commercially made piece. Arizona models may have offered a Polapink designed Pfalz in several scales but the 1/4 scale spinner I have from them was spun aluminum and this looks like a molded piece. Tom Polapink campaigned both a 1/5 scale and a 1/4 scale version but I don't think plans were published. I would point you at Arizona Models but I'm pretty sure the owner passed away and the business is gone. In terms of the scale, the upper wing chord for 1/4 scale is about 16 or 16.5 inches while 1/5 scale would be around 12.8. I don't have the figures right at hand but that should be pretty close. It looks like a beautifully made kit. From what I can see of the formers it appears that it is designed for a beam mount engine. For me that argues for an enlargement of an older plan but that could just be the designer's preference.