Welcome back to the hobby. I agree with everyone to choose another engine. I used to teach a lot of primary and I got so that I wouldn't waste my time trying to get a Magnum, RCCG, and there are a few other alphabet engines that I would stay away from, especially getting back into the hobby. You just don't need the aggravation of a half ass quality of an engine. The OS line used to be very good, but now that it is made in China, not so sure of the metallurgy quality. The OS .46 AX or FX used to be top of the line engines for the Sunday flyer .40 size planes. The other engine that I love is the Thunder Tiger.....NOT Super Tiger.....engines. A TT .46 Pro is an awesome engine. I could get it tuned and beat guys flying Jett engines in quicky races.
If you are going with air retracts, Spring Air used to be a good quality retract. Looses air pressure, the gear pop back down with springs. As the guys said, there are a lot of new electric gear and you will have to do some research. Electron gear are great, but not sure they make stuff for that small of a plane.
You didn't ask about radios. I would recommend getting what most of the guys at your field are flying. That way you get help with programming and set up.
Here is a site to get some of the good Ole pattern planes of the past.
Original Bridi™ Airplane Kits :: Buy an RC Airplane!

Good Luck!