Honestly I wouldnt even do the other mods you listed, you won't gain anything.
Stock 195 thermo is best, running colder plugs on a stock car will just reduce mpgs slightly and you want to run the hottest spark you can for the given mods.
Getting a different PCM won't help much as the stock tune is fine as it is. It already runs rich and will handle basic mods without any adjustments.
The real issues are flow, as in exhaust flow. Like an upgraded downpipe and or just buying headers to reduce engine knock and gain some HP and make things safe.
So you can't drop pulley sizes right now, you'd just be hurting the motor and likely someday looking for a use long bock to throw back in it after a piston or 2 dies.
