[Tim89LXvert]

Congrats on your purchase.

Being an 86, you have some performance hinderances compared to 87-up 5.0s.

The heads and intake are more restrictive than the 87-up versions. If you are going to get a better intake, you will definately need to step up to better heads. You should be able to find some used GT40 irons for not too much money.

An additional area of concern that some pre-87 owners should be able to help you are on is piston clearance. The 87-up pistons were notched for valve clearance. I am not sure how big you can go on the heads before that will become an issue.

gtsr is giving some very good advise too. Work from a plan.

First make sure you basic systems like cooling, braking, drivetrain are all sound and in need of repair. If you need brakes, or overheat, or have worn items, mods will only make you break sooner.

A few basics first that you can use to build on later would be:
1) A good tune-up with plugs, wires, cap rotor, fuel filter along with gtstr's recommendations (some of this you already have done)
2) Remove air silencer and install K&N panel
3) Advance the timing to 12°-14° BTDC (as long as you are willing to buy premium)
4) Underdrive pullies, good bang for the buck
5) Free flowing exhaust (unequal shorties, off road h-pipe, and 2 1/2" cat back is the cheapest way)
6) Gears, 3.73s are pretty popular. I love mine, and they really wake up the car
7) Aftermarket shifter. This is something you will not regret
8) Adjustable fuel pressure regulator, good for tuning
9) 180° thermostat
10) larger TB as gtsr recommended

Most of these outside the exhaust and the gears are pretty darn cheap, but they make a good improvement.

After that work from your plan, and your budget. Plan how and where to spend your money, and don't be afraid of some used parts. They can save you alot of money. I have used quite a few myself.

Good luck, and enjoy!!