Here's the motor with both heads installed and the valve train completely adjusted. As Cliff noted, one benefit of adjusting a Pontiac valve train this way is that you can clearly see when the lifters are on the base circle of the cam.
Another thing to watch when rebuilding a Pontiac is to make sure that that valley pan is absolutely clean. Over the life of the motor the valley pan collects all sorts of gunk and grit. If it’s not perfectly clean, whatever junk left in the valley pan will drop down inside your brand new motor. One way to make sure the pan is clean is to break the spot welds, clean the sheet metal, and re-weld. My machine shop used special brushes and water jets to make sure all of the grit was gone. Even so, I took the time to examine the pan with a flexible light just to make sure all was good.
It's also important that the valley pan is clean and dry so that the sealant can do its job. Don’t over tighten the valley pan bolts. Fifteen foot-pounds all you need here. In order to avoid oil seeping around the valley pan bolts, we placed a little dab of sealant under the bolt heads.
Here is the last look at the valve train before the valley pan goes on. I didn't talk much about installing the cam because I didn't get any good pictures. Like Steve says, the usual process is to remove and install the cam several times while checking fit and clearance. However, this cam required some effort to install. It was okay, meaning that we could rotate the cam by hand, but we didn't want to take the chance of removing the cam and installing it again with the additional chance for nicking cam bearings.
This is also the last chance for adding cam break in lube and double checking that everything looks good. If you are the builder, you can spend as much or as little time as you feel comfortable. Given the stories I had heard about flat tappitt cams rounding lobes during break-in, we chose to use lots of cam lube. You can also see the silicon sealant that we applied to the sealing surfaces; again, these surfaces must be clean and dry if you don't want leaks.
Final note about the installation of the valley pan - once this is bolted down, there is no more ability to add lube to the cam lobes. For this reason, you don't want to rotate the motor any more than is absolutely necessary between now and the time it’s fired.
Here is the motor with the valley pan, balancer, and distributor installed. Is very important that the distributer is installed correctly so that the motor will fire right up. Incorrect timing is a common reason for a no start condition with rebuilt motors. (And remember that the more that motor spins without firing, the more cam lube is wiped off the lobes.)
Here is another Pontiac issue to deal with. This problem happens when using 1967 - 1971 intakes with 1972 and up heads. The exhaust crossover on the right side of the manifold is taller than the matching opening in the head. The fix is to use the small opening gasket (pictured here) with a shim that covers the intake manifold opening. Jim Hand offers a good illustration of the fix
http://www.dapa.org/jhpages/jhand9.htm.
Here is the completed motor. The fuel pump has been added as well as the intake and carb. Compared to the work we had been doing, this all seemed pretty simple. Even so, we could not get all 8 manifold bolts to thread. We decided to pull the manifold and elongate the bolt holes rather than risk a cross-thread this late in the process. We used thread sealant on these bolts to avoid sucking oil under decell.
My machinist recommended breaking in the motor on an engine dyno. To me, that made sense because 1) if there were any problems in getting the motor to start, it would be easier to work on the motor out of the car, 2) fixing any leaks would be a lot easier on the stand, and 3) breaking the motor in on the dyno allows for tuning during break in.
Here’s the motor ready to go to the engine dyno.