Tom,
I think the low aspect ratio and the small (by today's standard) tail section limited its stuntability also.
I was fortunate enough to get the full-size plans when John Pond was still around. I checked Tony's site. That is very nice of him to post it. I think my the pages in my mag is as brown as his.
Mine will be powered by an Atwood Shriek .049 this time. Flush-mounting the Thermal Hopper is a pain in the...neck. The thermal Hopper made it balance well though, and it flew like a bat out of a cave.
I guess with its small size, any old .049 would be good. A modern one, TD (?), Norvel, etc. would be way too much. Moving the firewall back and powering with a Black Widow might work. Probably power equivalent to the Thermal Hopper.
George