Of course it can be converted, even just using "LAR" (Looks About Right) type of engineering. This is a sorta antique, vintage looking R/C sport model with a largely open rear fuselage. Kinda sorta Bleriot looking or Fokker Eindecker. Lou Woolard had a similar model published in the mags back in the 70's I think. I don't have any experience building an Elder 40, but if it has a removable wing, you canmake it real easy and just mount the bell crank in the fuselage, and run the lead outs below the wing through some sort of add on guides at the wing tip. Tape off the ailerons and rudder, set the throttle and lock it down and almost an instant sport model! It's been done with R/C models before, and has even gon the other way, with replica airplanes of control line models but tweaked a bit for optimum R/C performace. I think I have even seen an article while flipping through mags recently of some one doing an R/C Junar. About half of the SIG Fazer fun fly models were built as C/L stunt models and they eventually added conversion instructions to the kit booklet.
Good luck and have fun,
Dan McEntee