I'd guess it's the valve springs. They are a very weak point and if they are soft, your valves will float at higher rpm and keep you from revving. Try setting your advance to about 17 degrees at full rap and see if that helps.

Also have someone with an adjustable timimg light check total advance (combination of mech.& vac.) should be about 32 to 34 degrees. Also verify the accuracy of your tach. A tune up shop can do the above quickly and cheaply.

Phred