I am somewhat newer to gasser also,so I dont have tried and tested answers,try the gasser forum under giant planes,good info there.
Some say a metal rod is fine,some use plastic ball links at each end.main reason for this is that RF noise can be transferred from engine back to the receiver easily,and cause range and glitch problems,so a plastic or Nylon clevis helps.
Browse thru some of the pics in the giant scale built threads.