H power loss

Have you checked the carb float level? Also, be sure the float is not cracked/leaking or binding. This probably isn't your main problem, but can make other problems worse.

When your turning the mag L and R, are you sure that you have loosened the correct bolts? I'm not familiar with adjusting mag timing but the manual explains that the dist cap must be removed and the impulse coupling timing checked. Look at a manual, it will make more sense. Good Luck.

Jon

If you don't want to bore/stroke, start by getting a distributor and make sure the advance mechanism is working. You can get more advance, easier from a distributor than the mag. Can you back out the load screw on the carb enough to over fuel it? If not, take the carb apart and make the holes in the main jet tube larger, and possibly the jet too. Make small changes and test. While you have the carb apart, try a larger venturi. You can find them at junk yards, or you IH dealer. There is a number cast onto the unit, the larger the number the larger the bore. Next you could use a head from a 300/350, and if you are going to use the head you should also use the manifold and carb. Have the head ports cleaned and smoothed, and plane the head to increase your compression. You could also install larger valves in the head, several automotive valves can be made to work and they are much cheaper to use than the stock replacements. You could also install a 350 camshaft, or have yours reground.

Of course, anytime you change or improve the engine you will need to re-adjust your timing and carburation to take advantage of the change.

Jon Aller