351W conversion
Since you are going to be removing the computer system, I would recommend going with a good aftermarket electronic ignition, or you could rob an old points unit and put a Petronix conversion kit in it.
A lot depends on what you are going to do with the car. If you are planning to stick with the stock tranny and gears, I would consider a cam in the neighborhood of 200-210 degrees duration with a lobe separation of 109-110 degrees.
As luciano stated, you will need to change the front timing cover if you want to run a mechanical fuel pump, and, if so, be sure to get the correct fuel pump eccentric for it as they made a couple differnent designs and miss matching them can create a prolbem, with the eccentric eating a hole through the timing cover, causing aluminum filings to fall down in your pan and pass through the engine, resulting in 0/0 tolarances and a locked up engine.
Being you are running a heavy car, I would go with an intake geared more for bottom end power, meaning mainly a dual plane, and a 550 to 600 CFM carb. As for what brand or model of intake, everyone has their own ideas on that. I would look at intakes designed to work in the 0-5500 RPM bracket.
As for exhaust, finding full length tube headers could be a hassle, so I would opt for a set of shorties designed for a mustang.
Would be hard to go wrong there.
As for timing chain and gears, I would go with roller chain, as they dont wear as fast, but then when considering a stock replacement steel gears and standard chain should be good for 100,000 miles, that could be a moot issue.
Are you planning to do any work on the heads?
If so, are you going to do it yourself or have that farmed out?
If you are going to farm them out, you should consider going with a set of Roush or World Jr steel heads instead. By the time you have your stock heads worked over with porting etc, you would have as much in them as the cost of the aftermarket steel heads. The reason I would go with the Jr heads is that they run the 1.94/1.60 valves and since you arent going to be running a mega rpm engine with this car, going to the larger runnered and larger valve (2.02/1.600) isnt needed. Going with the larger valves would also require having your pistons flycut for them.
If aluminum heads are your thing, I would go with a set of Twisted Wedge, as, they are probably the best bang for the buck, in that they have the 2.02/1.60 valves but due to the head configuration, unless you go with a duration of more than about 240 and a lift over .520. you dont need to have special valve reliefs cut in your pistons, as you would with heads that have the conventional valve layout, when using the 2.02 intakes.
The best thing to do, is to realistically decide what you will be doing with the car the most. If its going to be a daily driver, then keeping your cam etc in a civil mode for everyday driving is imperitive.
It is amazing what gains can be made with just mild hopup touches. Its very easy to put an extra 75-100 hp under your hood without having to turn your engine stratospheric rpm.
If you are wanting to go from mild to wild, then you will need to spend some bucks on other things as well as the engine.
One thing that will help your car is a good shift improver kit in the transmission. They go a long way to reducing wear and tear on the slush box. A good grill mounted cooler for the tranny, bypassing the cooler in the radiator, is also highly recommended.