Manual brakes to power brake?

[oldblue1968chevy]

been reading some faq on how to make your manual drum brakes, power drum brakes...looks seems pretty easy/cheap.

I understand it all but the underdash part.

undo mc from firewall, get the booster in there gently get a brass T for the vacum lines...can i use the vacum in back of carb. between carb. and distributor?

can somebody explain what im supposed to loosen/change under the dash, and when i go to hardware strore for the T fitting, can i just take the fitting off my truck at the store, bring it in and tell em i need a T, come out of the store, and put my fitting back on and drive back home lol, my trucks and a driver, and my only driver, not a project lol...

heres a link to the writeups thanks!

http://67-72chevytrucks.com/vboard/s...d.php?t=163387

theres another one but i cant seem to find it, THANKS!