So...

what of that pumped Hanno on a 12x10 or 13x9? Will certainly has all the RPM figures for various props on this beast. A YS 61 AR would be another interesting option but I understand not available.

I'd be inclined to put a high thrust engine into the EU-1A and turn a big prop compared to the standard 11x7-1/2 of the day and have that engine turning at 9.5-10K RPM.

David.