Hi!
As Ed and Jimmbbo has already said "all engines of the same size have more or less the same power" and that the power or hp ratings the modelengine manufacturers state is worth nothing ....I totally agree with this but there are still certain things to consider when choosing an engine and that is that there are small power and weight differences. For instance a Rossi 6,5cc (.40) or 7,5cc ( .45) is a rather good engine, sturdy built and rather powerful as sport engines go, but it is 50 gram heavier than most other 6,5-7,5cc engines. In a small fast airplane this weight could be too much. So picking a light engine is what I think is important
Another example that hp ratings is noth wort a thing is comparing a .40 pylonracing engine like the Nelson FAI that produces 3,5hp at 27000-30000 rpm or better still the Dutch MB pylonracing 6,5cc engine which produces more like 4 hp at 30000rpm.
Would these engines be better to use in a ..lets say an aerobatic type of aircraft like the SIG CAP 231 EX (span 185cm) than a 25cc (1.50) engine producing around 3hp ?! Hell no! These small pylonracing engines develop their power at such high rpm that we need 7 1/2" props and super sleek airplanes to make them perform...but perfom they will reaching speeds around 375-400km/h (over 200mph).

So picking the right size of engine for your airplane is very important.
I don't know the size of the airplane you speak of but expect it to be around 170-175cm in span as you had .90 engine...... so going to a 120 fourstroke (or a 110 YS) might be the right way to go.
Choosing the right prop is also a very important thing to consider..You can take two fliers using exactly the same engines and fuel...but using different props ....there will be a large difference in performance between these to engines/airplanes.
Among competition oriented flyers there is a general knowledge that APC makes very good propellers. For the larger engines 20cc and up the German Menz (wood) and Tjeck Mejzlic(carbonfiber) are good.

Regards!
Jan K
Sweden