Thanks everyone for the cam insight. Based on the input I think the E4 will be a good fit for the '57 Tbird with a Ford-O-Matic , but will talk to the machine shop about the possible vacuum issues. FWIW, I am using the fuel pump that incorporates a vacuum boost chamber ( at least I think that is what it does) so the vacuum may not be an issue. That being said, I keep getting surprised on this car so will definitely perform some due diligence there. 

Thanks again to everyone for their ongoing help. 

Getting adequate oil to the rockers is an issue with these engines.  The oil holes in the head are small and they tend to clog up though the years.  In addition, the oil runs through a dog leg that you can see with the heads off. Milling the heads can make this worse. Mummert cuts the center cam oil grove deeper to .030" in his cams to increase oil flow. Before I installed my Isky cam, I measured the cam grove depth and found it was .018" deep.  We put it in a lathe and cut it to .030".  I tested the flow manually on the engine stand and it made a big difference. So much so that I was afraid I would flood the heads with oil.  When I ran the engine, I found it to be perfect.  I left the value train stock and it's been working for over 3,000 miles. There are threads on this subject if you want to learn more.  This forum is a great resource of information.  It's wonderful that so many people care about these old motors. 

The vacuum boost section of the pump is intended to compensate for varying manifold vacuum while driving. It is considered operational only when pulling 10HG with manifold vacuum source removed (test procedure).

Also, if using a vacuum brake booster, it needs to see at a minimum 18HG to be fully operational.

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Many moons ago I added a vacuum tank to the brakes on a car I had because of the cam. The tank was from a 1970 Galaxie that operated the headlight covers. I had a vacuum gauge attached to it to see how much was there. I did have to make sure the vacuum was up before I drove off, but I could get an incredible amount of stops out of it once vacuum was up.

Thank you for this. It's great to have some actual numbers to check against. Right now the brake booster is non functional so I shouldn't have a problem, but will be rebuilding it as the project moves along so will need to figure it out. I have seen many vacuum canisters that could be used and seem to remember some active 12V vacuum pumps that can be used so I think there are many solutions for the brakes if I need it. Today's project is replacing all the vacuum lines and cleaning up all of the exterior engine parts to get them ready for painting.
The machine shop is starting to gather the parts so I hope to have the engine back in a few weeks and want to be ready. 
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