To be honest, I would have guesed that rolling into the bank would suggest a nose heavy condition with the plane wanting to drop it's nose into the bank to steepen it rather than drag it's tail a bit and hold the nose up if the CG was more rearward.

If built according to the plan, the CG should be about an inch forward of the main gear with an empty tank, as they tended to put the main wheels only about an inch at most behind the CG so they could "rotate" scale like for takeoff.

Another guess might be the .80's running a larger prop than originally designed? I Know I can gain thrust going up in prop diameter with my Curare but anything over 11.5" and it just feels like the prop pulls and pushes the nose around a bit, where with the smaller dameters (~11") it's less noticable but the prop is less bitey.