C20 Introduction and (another) 8 Lug Brake Booster Question

[SaltyC20]

Hello everyone. I have been lurking for a while, dreaming up all the things to do on my truck. I recently purchased a 1968 C20. My first matter of business is making this piece stop! Along those lines I have acquired an 8 lug front end with disk brakes off a later model C20 to replace the manual drum/drum setup in the truck now. The front end I bought includes the stock proportioning valve, but the lines were cut upstream of the proportion valve.

My questions are around replacing the master cylinder and adding a booster.

In my haste, I ordered the master cylinder and booster off RockAuto for a 1974 C20, see link. The booster is huge! http://www.rockauto.com/catalog/rafr...&parttype=1884

Anyways, as you already know, the mounting pattern for this booster is different. What are my options? My first thought is to return this part to Rockauto and buy the booster from the 1971 - 1972 trucks, will that booster bolt in directly? Also, what if I ordered the C10 booster this time, it seems a much more reasonable size vs. the C20 booster. And one last question, how do I know which is front and rear on the master cylinder (image below)?

That's definitely more than one question. Thanks for all your help. I have a long road ahead of me (700R4, A/C, Bodywork, etc) but am ready for this new project.