[Jacques Reed]

Hello Harle,

Your problem could be wear in the clutch release shaft and their bushings.

The shaft can wear appreciably as shown in the attached photos along with their bushings allowing the shaft to twist in the transmission housing. Note the very noticeable ridges at the the bushing areas.
Years of civilian owner neglect is the probable cause if not lubricated regularly.

I replaced mine with NOS items but they should be available from Ford Flathead V8 suppliers.

Hope this helps.

Cheers