Another opinion...

I am just finishing up the SE ARF. I built the kit several years ago. It was an okay airplane, but just didn't do much for me. I had an OS 46 SF on it. All in all, a nice model; but rather ho-hum.

Then I flew a pal's SE ARF with a YS 63. This airplane was MADE for four-strokes. With a big, low-pitch prop, the stump-pulling thrust of a good four-stroke makes the model come alive.

Okay, all of this is subjective. I am in the process of getting rid of every two-stroke plank engine I own; going strictly to four strokes.

For me, the much greater thrust and acceleration of a properly-propped four stroke just beats ANY two-stroke on any day. YMMV...

I will say that the Saito 91 is probably a bit much. But it has been done, and as long as you give yourself some more prop clearance, it will work. Do a search for TNT Landing Gear Products. They make a custom SE gear that gives you the necessary clearance. You have to drill your own holes; big deal.

Steve