I assume that Airtronics/Sanwa servos are compatible with a Futaba/JR Rx. (I know that Futaba servos can be used with Airtronics, if you cut off the little tab.) If I go with Futaba it would probable be the 8JA:
http://www3.towerhobbies.com/cgi-bin...&I=LXBWGR&P=ML