I was mistaken about Vector, but Silverwings has the Lycoming R-680 listed, no other information, might be worth an email if you're interested.
Cheers,
Dave.
Ah, now I see why I could not find it. The problem is that PT-17s in 1940s, as my example, were powered by Continental R-670 engines, not Lycoming...
Thank you, Pup7309 for your comment and interest.