One inch throw on the clutch slave arm sounds sufficient. Maybe the new clutch slave + arm is slightly shorter? Did you get a rebuilt Lockheed 99364C slave or a reproduction item? You can probably check the distance from the bell housing to the end of the new clutch slave + arm is the same length as the original clutch slave + arm.

Did you replace the pilot bushing when you replaced the other components? If you did replace it, you needed to soak it in engine oil for a day or more prior to installation.

Is the replacement throw-out bearing the carbon-type and did it look like the same size as the one that was replaced?

I have a couple different pressure plate designs.
What is on my car now. I think it is Borg & Beck:

And a replacement pressure plate, which I think is made by QH (Quinton Hazell):
I have not tried the QH pressure plate. I picked it up from a fellow sunbeamer to have as a spare. Supposedly, it came off a series V and worked …

And I am assuming you have the 7-1/2" clutch components…