The Magnum XLS .36 and Magnum XLS .52 (and ASP equivalents) will make nice CL conversions. Run a 2-2-2 sort of run and a .272" venturi with a .157" spraybar through. Randy Aero can provide venturi, spraybar assy and his excellent CNC tube muffler. The Thunder Tiger 11 x 4.5 is wonderful match for the .36 and I'd start with the 12.25 x 3.75 or 13-4 APC on the .52.
I ran a used XLS .36 for years and years on a Fancherized Twister. But I did use a .46LA muffler on it, because it needed the nose weight. I gave the plane/engine to Tim, who crashed it due to not following directions (

). But that little .36 had about 20 gallons of fuel through it, and it would still do long strings of 1-flip starts. I got as many as 12 or 13 in a row. It really wanted to run! I've run another in an Olympus with a Randy Aero CNC tube muffler, and it also ran very nicely, but only have put a few runs and flights on it.
The ASP's can be gotten via Hobby King, very reasonably. Magnums come from Hobby People, a bit more dear. They still sell the .52, but not the .36. The .36 you want has the "weedeater" style cylinder head...not round. The XLS .40, .46 and .52 are made on the same case casting, so the .52 is the lightest per cubic inch by far. It's the one you want!

Steve
Edit: HK doesn't seem to carry the ASP version of the XLS .36, so maybe it's a gone goose. Too bad. The ASP .52 is here:
http://www.hobbyking.com/hobbyking/store/__10726__ASP_S52A_Two_Stroke_Glow_Engine_w_Remote_HS_Needle_Valve.htmlYou're given the choice of a remote NV or a NV mounted on the throttle. I always opted for the remote NV, simply because the remote is an excellent unit, and can be adapted to use on combat models and trainers. The .52 will be a good equivalent to the late ST G.51...about 10.5 oz plus muffler.