The old day readings for 200 Mustangs were like 125 hp gross, which was less than 67 hp at the rear wheels, and about 87 to 91 hp at the flywheel (back of the engine, as installed with all ancillaries)
Basically, a stock 200 kicks out about 87 to 91 hp at 3600 rpm, and about 150 lb-ft of torque at 1800 rpm.
When you add better ignition, it won't give much extra power, it will just stay in tune longer, and idle better if the thing is set up correctly and you don't have any 'dud' parts. Your mpg improves
A well tuned 2-bbl 5200 or 32/36 or or 2100 or 350 cfm carb on a Stovebolt or Clifford adaptor will give an extra 10 hp, but only when you have improved the exhast. Adding tubing headers with a good Mustang GT style V8 style exhast, will yield a further 20 hp. Taken together, you get 30 hp extra, but on its own, without the better exhast, , the carby improvement is not worth anything.
Its not hard to see about 115 hp in there. Peak torque goes way up to the 170 lb-ft 80Stang saw that with just a stock 1-bbl carb, headers, and a 264 cam. A 2-bbl and stock 252 cam, plus good exhast won't get any better than that.
After that, the cam shaft is the major gate keeper to power and torque increases. 1.6:1 rockers can help heaps, but are not really a bolt on unless you are using a later 1978 on wards head, a much recomended swap. A latter head will help performance and economy, but the stock cam is only open for 252 degrees of the 720 degrees cylinder turns cycle. A cam like this will restrict the power and torque increases.
When you add all these bits together, the bigger 2-bbl carb, an aftermarket 264 degree cam (which stays open longer each cycle and also lifts the valves higher) , and a later head, and rebuilt the engine with flat top pistons, you'll see a huge increase in power and torque, way up over 120 hp is certain. That will be a please to drive.
The change from a 3-speed auto or manual to a 4 or 5 speed manual gearbox, you free up what feels like 5 hp on the open road, and about 25 hp when leaving the lights! Its not an easy swap for a beginner, but there are 3 to 6 mpg gains on the open road over any automatic Mustang if you update the gearbox.
