How about a MARUTAKA Curtis Hawk P-6E ? They are the old royal kits still available thru hobby barn. It takes a 60 -91 four stroke, I'm sure the 70 will fly it just fine. These were rated back when 91's put out the same power as a modern 80 four stroke. They also make a pitts s1 and a pitts s2 in 1/5 and 1/7 scale, the only pic I could find on the web is the s1 pitts version.