NEED ADVICE and or OPINIONS

[87 GT MUSTANG]

I noticed i am leaking oil all over my tranny and it is causing my tranny to slip once in awhile. My problem is the rear lower intake seal is gone. My 1995 mustang GTS currently has 158,000 km's and if i am to pull apart the upper and lower intake, do you think i should pull the heads as well and clean them up?. Before i go through with the tear down i am going to do a dry and wet compression test to check for any internal engine problems as i have had oil squirting from the top of my dip-stick when i hit the loud pedal, i have replaced my PCV valve and PCV filter and checked the lines and they are fine. I am thinking of getting my stock components port matched as i am on a very tight budget. I am looking for the best possible route for my car as i am not selling it anymore and wanna do some stuff to it while i have the motor apart. What would be some of your suggestions as to what to do with the motor while it is apart?. I am on a very tight budget and am looking for the best bang for the buck while bringing my pony up to par. I am looking to gain some more power and a sturdier motor ofcourse and will be doing most, if not all of the work myself (except for port matching)