spark plug heat range

i run the race at the track cause i bump the timing up to 36 going to try 38 and pump with it at 32 and the 111 is because thats about the only thing i can get around here except 112/116 we have 100 at the pump at a store out of town but its just a few coins lower than the 111...i do need to try it and see how it react cause it could be better,just never tried it....
340 bored 30 over
j heads mild port work 240/140@500
comp cam soild 520/540 with 1.5 roller rockers
dome tops on eagle h beams
stock stroke 3.31
x-cal intake with hp 950 86/88 jets 31 shooters and 4.5 pv in the front blocked back
mp dist. locked out
727 with 9.5 verta (5000)
4.57 gears with 27/10.5 qtp (changed to 28/10.5 m/t slicks now)
comp 11.5.1 plugs look good will take some pics next time to post for more info on them....
car runs 7.54 1/8th mile with poor 60' 1.67 it leaves good the burn the tire off..(changed the frontend around a little so hope it works better) oh i have 02/03 ss on the back 90/10 front and mp long drag shocks back....????for you did you have to make alot of changes to use the mustange body???or you useing the tube frontend????if so did you still have to make the headers?????got a freind that wants to try it.....did you use a motor plate or fab up mounts??? whats your back susp??? sorry so many ??? and if you can suggest something fo me to try out shoot ill try anything to get it faster,my son gonna get the seat time this yr. so it will be down on weight im 240 hes 160 so that helps hahaah