Break the engine in with the PCV hooked up.  If you have enough blowby to overpower the PCV, then you’ve got a problem.  You’ll want to get the engine on the road as soon as possible after cranking it so that you can get some ‘heat’ into the rings and get them properly seated which means having everything hooked up so you can do this in a timely manner.  Too much ‘no load’ running or idling on a freshly rebuilt engine can glaze the cylinder walls and make ring seating just that more difficult.

You still need the 20minute/2000 rpm breakin procedure.  If the cam is going to go bad, it’s going to start doing it within the first two minutes of running but it will take up to twenty minutes to destroy enough of the lobe and lifter to make it noticable.  But that intial breakin period in the garage stall still gives enough time to check for oil and water leaks and get the tuneup in the ballpark before hitting the road.

Do not get to crazy over some metal in the break in oil. On my 312 breakin and 500 mile oil changes I viewed the oil in the drain pan in bright sunlight and the oil looked like metal flake amber paint.

Scared me but the oil pressure has not changed since the first time it ran and runs great. Only problem I ever had was the oil consumpion went up to a quart in 500 miles on this years ford carslile trip and also on the way to the CVA convention. It turned out to be PCV related and after disabling the PCV it burned nothing on the way home from CVA.

10,000 miles on it now and it's still runing great and a recent blackstone report finds no problems.

Lengthy so bear with me.

The camshaft breakin rules haven’t changed much in 40+ years for flat tappet camshafts.  Neither has the fact that if a camshaft is going to go bad, it’s going to start do so almost as soon as the engine fires up.  Like John mentions, if something is visibly or audibly going awry before whatever allotted time period you’re using is up, then shut the engine down and check it out.  I have very few issues with camshafts and attribute that to just paying attention to the little details when putting the engines together.  It doesn’t mean I still don’t cringe everytime an engine is cranked up for the first time and has to be run  the prerequisite amount of time to insure that another camshaft has passed the test.  I save the diesel oil for diesel engines and use only quality gasoline oils in gasoline engines.  Zero issues but I also adhere to the specifications in the API bulletin as far as which oils are best suited for a particular build.  I’ve a list here with over two dozen items that can cause premature camshaft and lifter wear.  If any one of these items is missed or not addressed, then it doesn’t matter if the rest of the items were covered as it’s an all or nothing deal.  All items must be covered or the premature camshaft wear problems come back to the forefront.

A plus side to running the engine at a high idle speed and for a predetermined amount of time is that the engine is allowed to thoroughly warm up and then heat soak once it’s shut off.  If the engine is allowed to completely cool before being restarted, then valve spring life is lengthened significantly.  If the engine is revved without this cool down time, valve spring life is shortened.

Cylinder wall finish is extremely important for initial seating purposes.  If the machine shop doesn’t ask what kind of rings you’re running, then there’s always the chance that the ring finish being put on the bores may not be right for the rings you’re running.  It doesn’t get any simpler than this as rings will start seating as soon as the engine is cranked when the correct finish is being applied in regards to the rings being used.  It’s not until the rings are heat loaded that final seating can take place.  Some ring finishes require torque plate honing while others don’t find that as necessary.  I’ll add at this point that the correct oil should also be used during assembly and during breakin to promote ring sealing.  Because of the critical nature of ring seating in a new engine, I always recommend against the use of synthetic oil until the engine is thoroughly broken in.  Just my opinion but is based on several engines I’ve seen broken in with synthetic oil that did not fare well.

Here’s the draft for the new (proposed) standard.  You’ll want to look for the phosphorus if wanting to know what’s happening to the zinc.  Phosphorus is the part that’s being mandated for reduction, not the zinc.  But for zinc to do it’s job, phosphorus points the way as it is the particular component that is attracted to high heat where metal to metal contact is taking place.   Zinc simply follows the phosphorus and plants itself between the metal parts that are causing the high heat as the anti-wear part of the duo.

http://www.api.org/certifications/engineoil/upload/ILSAC_GF_5_draft_Nov_19_09.pdf

Doing a search for American Petroleum Institute standards will probably find you the current standard.