Where's the Wow?

Hook up your vacuum gauge with a long hose tap the gauge to the windshield or were you can drive it and watch the gauge and see what you have for vacuum while driving down the road. If the vacuum drops way off when driving you could have a plugged up exhaust, bad muffler, pipe kinked, you might need to change the springs in the metering rod pistons to a lighter spring so if you know the vacuum you can get the correct spring. I know you are getting a lot of advice do the easiest things first. drive it with a vacuum gauge, pull the left valve cover rotate the motor till its on overlap and look at the balancer should be close to 0. Do like 318willrun said mark the push rods and see if they rotate when engine is running and just watch all the valves move they should all be the same.