I would look at the shifter and all bushings,make sure the lever arms are properly centered in neutral.
If the shifter is sloppy it can cause two transmission arms to try and engage gears.
Once in gear is the clutch pedal a light switch or do you have good take up travel?
The loose pivot may not be helping ,it does sound like the clutch is not releasing ,what about shifting to other gears ,engine running at a stop?
I had Bill Heeley restore the factory shifter. It's tight and adjusted correctly. The nuts haven't shifted and it's smooth while it's not running.
No bushing issues with any linkage. I am leaning towards the fact the pivot is loose. I thought with all the years experience here someone had a similar issue.
There is VERY little free free travel before it picks up. I did adjust the lower rod assuming the problem was the clutch had broken in and it just needed to be a bit longer. I also used the old trick of using a 65-6 emergency brake lever spring and running it from the lever to the lower control arm pivot. It keeps the throw out bearing from riding the plate.
I know many have ran into unique issues and I hope the vast experiences would yield an answer to unusual situations.
On the rocker shaft two of the thread inserts in the Edelbrock heads had started to pull, so the nuts on the studs absolutely weren't at 50lbs. I have a feeling the shaft was flexing being it was two studs on one end. I am going to try and make the repair on the engine. I came up with an idea for a drill and tap guide. The machine shop in our repair facility is going to CNC it for me. I ordered a Big Sert set for 3/8-16 to make the repair.
I would assume Edelbrock would have a lot of insert failures being they use a standard helicoil insert.
Thank you all for the information.