Although the outline appears similar to the Klemm 25, the Moth Minor is a quite different aircraft and it would be a lot of work to convert one into the other.
If you want to go the ARC route this [link=http://www.krick-modell.de/shop_fachhandel/produktdetailseite.asp?artnum=10270&grp=0,4,3]Krick 1:4.5 Klemm 25[/link] would be an excellent choice. Wing span is approx 113 in. and the weight is only 16.5 lbs.
If you would like to build a smaller Klemm 25 I can recommend the 1:7 scale [link=http://www.krick-modell.de/shop_fachhandel/produktdetailseite.asp?artnum=10170&grp=0,4,3]Krick Klemm 25[/link] from personal experience. It is an absolute delight both to build and fly. A small OS30 or Saito 30 four-stroke engine is more than enough engine.