That is basically the technique I've used in my 54 235 transmission installation, with the exception of installing the pivot ball. Once you install the clutch disc and the pressure plate you're not going to have enough room to center and start the ball.
The spring actually goes inside the clutch fork...it's got a groove to hold it and you just snap it over the ball once you get your fork in the throw-out bearing groove. With the ball in place you shouldn't have any problem getting the fork to snap onto the ball with your clutch assembly installed as well as the transmission bolted up tight.
I've pulled several down that didn't even have the spring in the fork. Once the linkage is adjusted down it will apply pressure to the fork and hold it against the pivot ball. However, this takes some fancy contortions as you need to hold it in place while you adjust up the linkage to take out excessive free play. Hope this helps.
Dave
