Tigerdude - if you think you will be flying out of grass, you might want to go ahead and get a little bigger engine. Get a .25 and just throttle back after airborne. I think that you will find more .25 available also. You could use:
http://www2.towerhobbies.com/cgi-bin...I=OSMG0525&P=7
or even
http://www2.towerhobbies.com/cgi-bin...25&FVPROFIL=++
I would prefer the FX myself but if money is an issue the LA would do for this plane. The FX is a better built engine with more power and better suited for use in later planes of similar size. It also has ball bearings.
Your budget is a determining factor. Others will recommend other engines I am sure. These are 2 I am familiar with in this size