Have you talked to John and/or Paul? They have been running 914s for years on their planes. It would be interesting to know if they have had any cooling issues. What are your ambient temps?

I haven't flown in a couple weeks - had an exhaust leak to take care of. The new exhaust is installed, so I'll be doing some flying this weekend in 22-25 C ambient temps. If I transition to an 85 mph, 34" cruise climb at a safe altitude, I don't have any cooling issues yet. I definitely can't do 40" and 60 mph for 5 minutes.

Have you considered a heat exchanger like Dustin mentioned? That's probably way easier than relocating the oil cooler, and I'm not sure the flow will be me much better behind that little cowl opening than it is in the NACA duct.