shadow maybe you didnt read... he asked for a stock 84 hotair plug
run whats recommended in the owners manual ..i believe its a delco r44ts gap at .032-.035
no need to get crazy with tight gaps or cold plugs on a motor that wont see boost over 13 psi
the intercooled motors on pump gas modern chip are used to seeing boost in the teens , bigger intercooler and high teens to 20psi is possible at which time a colder plug should be used like the r43 , alky /racegas/ e85 motors see mid20s or more boost and thats when the plug needs to heat range needs be stepped up to an even colder plug like the R42 to prevent detonation from a hotter plug that retains heat
and as boost gets higher you will find the gap needs to be tightened to be able to spark under the extreme cylinder pressures