noob valve spring question

I finally got time to get this wrapped up. Using a mic I ordered, I went back and checked through all the installed heights. Some of my original measurements were close, but others weren't. So lesson learned there, use the right measuring tool.
The other thing I learned is (I think this is what happened) when I removed the rocker arm shaft, most of the pushrods stuck to the rockers and lifted up a few inches before falling back down. When I was done, I just bolted the shaft back on and didn't realize I was supposed to make sure they weren't hanging up on the edges of the lifters. The second time around I was careful to make sure they were seated properly and everything went smoothly.

So it's back to running but I still have the same issue where it hits a wall right around 4K rpm. Before I did the springs I went through the ignition as best I could. I adjusted the pickup/reluctor gap, cleaned the ground at the voltage regulator, tried with the tach disconnected. I even pulled the distributor, ignition box, ballast resistor and coil, connected them to a spare engine harness I have, applied 12V to the harness, put a set of old plugs in a fixture I made, then spun the distributor with a drill that's rated for 2500 rpm, which should be equivalent to 5000 engine rpm. All the plugs made spark up to full speed.

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I took a video of the above setup working if anyone is interested. Guess I have to upload it somewhere else then provide a link.

So I'm not sure what's next. I guess I'll post up on another sub forum. But thanks again to everyone for the tips with the valve springs. I'll get this car back fully operational one of these days, it's just taking way longer than I was hoping.