The round one is a Metering valve according to the firstgensite illustrated brakes webpage, but some also call it a hold off valve and it was used on 67-69 with front disk brakes. The rectangular looking block under and offset from the master cylinder is the distribution valve and also called the proportioning valve. And the one on the frame below driver seat is a Brake pressure regulator Valve some also call this a hold off valve. All in all too many darn names..lol That first link in this post (Metering Valve) is a little bit cheaper from right stuff then the $90.00 you posted and they are a good place to buy from, at least in my experiance.