The right pushrods?

Maybe an easy question, but I'll ask to be certain.

I'm replacing the stock rockers on my 360 with adjustable rollers. I now need to replace the pushrods with ball/cup ones. How do I determine what lenght rod I need? Is it as easy as measuring the stock rods and just getting the same length with different ends?

If it makes a difference - I'm installing an Edelbrock RPM cam that says I need the adjustable valve train.