push rod ?

As to the short pushrod question.Theres only one reason for shortties. Machining stack up.
If the decks were machinerd for zero decks, and the heads were machined for compression,and maybe some custom valve work, then custom pushrods would be required.
In your case being as they are .250 shorter, thats an awful, awful,lot of cutting.By page, 3 I cant recall if you did a mock up.
Ok, I reread the thread, and see no mock-up
I would order an adjustable push rod and mock up for a geometry check, and then compare the needed length with the provided length, and see how close they are.Order if you need.
And once again, if the balls dont fit the cups, THROW them away.Quit speculating/fixating on the why of it.