MC Pushrod Question

Sorry man I tried to find the answer on this in previous threads and came up empty. I pulled the manual 9 inch drums off the front and rear of my 67, and I'm going with 11" drums in the rear on an 8.25 and 11.75" disks in the front. I also have the correct prop valve off a disk car. I assume from what I've read my MC pushrod needs to be changed, which leaves me with 2 questions:
1. What is the difference between a manual drum and a manual disk pushrod? Is it a length issue?; and
2. When I go to buy my new MC, am I asking for say any 70 to 72 a body piece with manual disks, or is there a preferred application?

Appreciate it fellas...
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