what are good spark plugs to run on a 340 and gapping ?

About the gap... Is that a function of the ignition system? I know stock is 0.035, but when my car was put together, the guy said he had to gap the plugs (I assume stock type) at 0.055 to eliminate some hesitation or something. It's got the REV N NATOR box and a high performance coil in it.

.055 thats a lot i run a full msd system and plugs are gapped at .045..