I have no issue doing head work especially on the exhaust side. That is were the 'B' head is weakest. Again, doing cams is big money for a small gain. There are cams out there out of an Aviator and Mustang that will show some improvement but the bang for the buck is not there.
My advise to guys on a limited budget (which most Mark owners are) is to do the bottom end with rods and pistons, (even the cast crank is fine to leave alone) so the motor can take some boost and put a centri blower on it. There are guys working on turbo kits and most will require a new k-member but those are a ways down the pipe yet. Our motors were blessed with a good stock maf, decent injectors, good heads, and a return style fuel system that only requires a bigger pump to put out 400 rwhp. Replace the injectors and you can see 450-500 without a ton of work. Even the coil packs or COP are decent enough for spark.
The tranny is another weak spot. I would always beef that up. For $1600, you won't have to think about that component again. Do some posi gears with some 3:73 for a boosted application and you have yourself a very nice street car for a reasonable sum of money.
Also make sure you replace ALL the bushings front and rear, especially if you have lowered the car and make sure to get it all aligned properly. Bigger sway bars front and rear are also another good investment as the stock units are undersized for the wheelbase and weight of the car.
And as a plug for myself, I would buy the best brake pads I could and then send me the rotors and pads to have them cryogenically treated to increase the toughness and longevity of the brakes.
17's are the optimum wheel size for ride comfort and sidewall flex although some 18's look killer. Anything bigger and it will look like you are driving a wagon.
All of this is my opinion. Yours and others may differ.
