I'm sure the information that you receive by email will cover all of this as well, but I thought I would post the procedure I used to install the PCV valve on my 57 Ford 292:
1) Remove intake manifold and existing valley pan and replace the valley pan with one that has provision for the PCV valve (installed in the original rear road draft tube port in the valley pan) There is a valley pan on Ebay that would work:
http://www.ebay.com/itm/1955-1956-1...9037dbd&pid=100033&rk=2&rkt=4&sd=310872866460
I couldn't use this spacer plate with my installation due to having a 2-barrel carb and I could not find a spacer plate with the vacuum port, so I just drilled and tapped the intake manifold right behind the carb and installed a fitting. Either way would work, but for you the spacer plate would probably be easier.
The other thing I did with the T-Bird valley pan was to braze a plug over the hole in the port (in the baffle box) directly below where the PCV valve and grommet are inserted to prevent oil splash from reaching the PCV valve.
2: Install spacer plate under your carb (if it is a 4-barrel which I assume it is with your 312 engine). There is a spacer plate with PCV valve & hose on Ebay:
http://www.ebay.com/itm/1957-57-FOR...ash=item4861777e9c:g:I~cAAMXQiNdRcTXv&vxp=mtr
The PCV valve with this kit is probably a good fit for the 312, but if you purchase a PCV separately, you need to match the PCV (cubic inch displacement rating) as close as you can. I bought a PCV for a 1966 Fairlane w/289 engine that I bought from Rock Auto and it worked just fine.
3: Block off the original road draft tube on the lower front portion of the block on the driver's side. I just fashioned a plate from 1/8" steel and made a gasket to fit the opening. Some others have re-installed the original draft tube with the opening blocked off to keep original look. Either way would work, but I felt the plate was simpler.
That's about it. Good luck with your installation. I'm sure you will be happy with the end result (less oil dripping, less engine fumes in garage, even some improved crankshaft sealing due to partial vacuum in crankcase)
Dave