what plugs and Fuel pressure should i be running?

what plugs and GAP should i be running naturaly aspirated, with my combo i was told 3924's but what gap? NOW i have 3934's gaped .045 also what fuel pressure should i have i was running 45psi but the plugs were BLACK, and smutty.. so i know thats to much fuel. also the check engine light comes on time to time, even with less fuel but the car runs better with less.. obviously timing is set at 16 degrees someone hook me up with a lil bit of knowledge.. THANX

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SOLD THE 87GT, .. GT40, 70mmTB, 75mmBullet, 24lbinjectors, cold air induction, Edelbrok 6025 Rpm's, Inch phonolic spacer, tall FMSvalve covers, an SFI balancer, Canton 7quart, the shortblock... Lunati 51025 (224/232 .535/. 544 @112 deg) Ross lightweight pistons (10:1) Eagle H-Beams, Total Seal plasma Moly Rings, Clevite bearings, ARP throughout, FMS main Girdle&Studs, Forged Crank, of course HV-OilPump and hardened FMS shaft, Dual Friction centerforce, T5, and 4.10's Longtubes and 2.25 tail pi