dyerstown,
I have seven OS 40FP engines, and all of them were bought used for between $20 and $40. Chances are someone you know has one sitting around collecting dust. In fact, I recently saw an OS 40FP for sale here on RCU for $30 including shipping. Or check on ebay. IMHO, for a Stickit engine, the OS 40LA isn't a good substitute for the OS 40FP. On the other hand, Foamguy swears his 40LA worked great in his Stickit......where we just ended up swearing *AT* the 40LA engines we tried in Stickits and similar planes.

Paul,
For a pull-pull aileron, just mount the servo sideways inside the wing, through a hole cut into a rib. Go here to read a good web page by Bob Adkins on pull-pull systems, including ailerons. Then look at the PICTURES link to see a good diagram of a pull-pull aileron linkage setup.
http://webpages.charter.net/bobad/pullpull.htm

For even more info on pull-pull systems, go to Google.Com and do a search for [pull-pull aileron].

Coulter_Dean,
The answer to your question in another forum about the OS 40SF vs. the OS 40FP is that the 40SF weighs nearly 4 ounces more than the 40FP.....which makes the 40SF way too heavy for a Stickit.