I used electric on mine but the model needs a little right thrust and I did adjust mine with washers on the firewall. I'd make the offset thrust adjustments by measuring from the prop tips to the leading edges since it has a straight wing it makes it easy. If this matches the cowlings fit problems I'd say jack that engine around to the right and downward.
Mine has a 15 inch diameter prop so it yaws really hard left during positive pulls. Yours won't do that as badly with an 11 inch prop, probably. However the tail is small on this model and even after adding offset right thrust and seeing a big improvement in it's handling, I still use plenty of rudder.
I would suggest that you tape control surface hingelines of the ailerons at least. I noticed my model would tend to drop the left wing when pulling out of a vertical dive if doing a hammerhead or some similar maneuver and I thought the air blowing through the open hingelines might be the problem. Once i sealed the ailerons that problem went away. I sealed the elevator and rudder too, it tracks a little better in pitch, yaw is unchanged, it's pretty steady in all axis.
It's a really fun model to fly. It makes very stable approaches, with my big prop it slows very well in the pattern and I need to add a little power once I get the nose high to stretch the glide a bit. I land slowly and near three point. It will porpoise pretty badly if you try to force it on, it likes a gentle nose high touchdown. If you do get it to land on the mains gently it'll make a nice landing too, but the gear is a tad forward to make fast wheelies, maybe you can but I'm not that good!
Hope you find this helpful.
Chris...