head install tech ?

I'm in the process of installing a set of edelbrock heads and I have a couple questions.1st What plug should I use?,the instructions say 14mm x3/4 reach Champion RC9YC to RC14YC.What heat range Would be best? Here're are the mods I've made 65mm TB,Cobra intake,1.7RR,76mm MAF,19lb injectors.adjustable fuel reg,12 timing,headers and off road h-pipe. 2nd Should I use thead sealant on lower head bolts? If so what kind and will.it affect torque readings. Any Opinons on what hp i should be putting out. :shrug: