I have a possible clutch problem or am doing something wrong.
When I shift to high gear and let the clutch out the whole car shudders and then it slowly takes off in high gear.
Is it possible that the clutch is slipping? clutch spring weakening? adjustment? Driver needs a dope slap?
Check first the hand lever is forward all the way, so the clutch pack can close fully. Sometimes floorboard gets in the way of the lever travel.
Then, its probably the clutch pack, so remove the inspection cover and follow the Ford Service instructions to tighten the clutch plate throw.
Don't drop key or cotters or anything in the opening as you go about the fix.
With that done, check or readjust for 'free neutral'
Yes, it's possible that the clutch is slipping. Also possible that it's somewhat your driving habits at fault.
Before letting the clutch pedal back into high, you should pause a moment to let the engine speed slow down to better match the vehicle speed. Then let the pedal back somewhat quickly. This is easier on the clutch and helps to prevent chatter when engaging high. In other words, don't feather the clutch.
Try this first.
Another thing which keeps the parking lever from going all the way forward is the length of the brake rods. If they are adjusted too long, they will push the handle back while you are in low gear. Then when you let out the pedal to high, they will keep the bolt on the cam lever at the side of the transmission, which will cause the clutch to slip. With the parking lever all the way forward, push the brake rod all the way back without bending the rod. You should just be able to put the clevis pin in without binding. After you adjust the rods, if you find one brake tighter than the other, loosen the tight rod 1/2 turn and check brakes again. Do this by 1/2 turn at a time until you get the brakes even.