Hi Alan,
I have flown mine with a DS 40, L&J Fox 35 and a retimed Werba 32 (used that one at Brodak's). The DS 40 and Fox 35 seem best suited to it. I used shaft extensions on both and they balanced perfectly with out added weight to the tail. Both pulled the plane with no problem (36 oz) at Huntersville. (turbulence)
The Aero Tiger would be outstanding, but you will have to add weight to the tail. Same with the others.
I am putting the L&J Fox 35 back into it, as of Sunday night. (Had to do some repairs!)
P.S. The DS 40 needs a venturi in the 295-300 range (we found this out), and three head shims total (from Tom's directions) for 5%-10% nitro.
Bill <><