3DP,
It all breaks down to wing loading...
While the Ryobi is a very reliable motor, it has a few major drawbacks for your intended purpose.
First is weight, even with electronic igntion you will sit around 4 lbs ready to fly. This ties directly in to wing loading.
I couldn't find any info on the 25% but if I remember correctly it MAY just barely have 1000 sq inches of wing area.
You will be lucky to get the plane under 12-13lbs ready to fly and still have an airframe strong enough to support a gasser.
http://www.gsal.org/tools/Wing_Laoding.htm
That brings your loading up to about 28 oz ft. Flyable, yes....perfomance...no...you'll have to keep power on it until you land...it will be a tip stalling nightmare.
Imagine the waste of a good aerobatic airframe that flies like a heavy trainer...with faster roll rates....and a snap tendency...
The most thrust you'll get from the Ryobi (even converted to ignition) will be 14-15 lbs.
It really depends on how you want to fly it....but I don't recomend anything under 1200 sq inches for a Ryobi. My Big Pink (with ryobi TWIN ring version) is 16 lbs with over 18 sq FT of wing area... loading is around 13-15 oz sq ft. A very happy combo....
Recommended airframes for the Ryobi (Stinger 1.20, or UltraStick 1.20)....notice both have generous wing area.....
Recommended motor for the 25% - any glow 1.20-1.60 or maybe the newer generation of gassers like RCS 1.40/1.80 MVVS 1.40-1.60
I have the RCS 1.40 and its awesome...worth every penny....swings a 16x8 Bambula at 9100 rpms and whole setup is 3lbs with muffler and ignition.
Currently bolted to a GSP/CMP Katana.
So....I would seriously think about what direction to go from here....
Keep the Ryobi? - Get a different airframe
Keep the Laser? - Get a glow motor (or new generation lightweight gasser if you want gas)
I hope this helps....and I'm not saying don't try it....but be prepared that you more than likely will not get the results your looking for with this combo.
This airframe deserves a good strong, light motor...and the ryobi deserves a light 1200+ sq in plane.....
Good Luck!
Hope this isn't too much of a downer.....
CrazyHerb
www.crazyherb.com