I can tell you that the .65 has no problem with a 13/6 on the bench.
Just recieved a Tachometer and will run an LA-65 on the bench with a 13/6 and 12/6, and provide #'s if it will help.
Years ago I installed a Fox .40 sch/bbng engine in a 52" bipe. It was heavy but flew fine. After awhile I replaced the .40 with a Fox .60 non-sch. bbng. Eagle I. (both engines claimed near the same hp figures though at very differant rpms.) The .60 brought that plane to life! One of the things I learned from that experience was that fast engines need to be mounted on fast airplanes, and for the others, more torque and larger props work better on the slower ones.
I also believe that bipes have 2 wings. This says to me that a 52" main wing bipe is about comperable to a 104" monoplane in drag, and about 25% more weight. (just an uneducated guess) This tells me that your 72" bipe is about comperable to a 144" momoplane and about 25% more weight.
I think the LA-.65 would have no problem with this plane, but also believe a .91 sport engine with considerabily more torque than the .65 would be a better choice.