Re: Old school motor break in question
In my opinion all of the issues have been covered. Let me restate the issues.
What you are trying to prevent is a lifter/cam lobe failure. The concern others have addressed is the constant cranking causes the assembly lube to be scraped off. My concern is that after twenty years your assembly lube has become jelly, or a semi rigid plastic by now. It's ability to lubricate is long gone.
So now you have no assembly lube. The lifters are now relying upon splash lubrication which doesn't happen at idle. You want to rev the engine to slosh oil up upon the cam. You don't want to maintain any fixed RPM as that will prevent your lifters from wearing in properly (wear on one side instead of rotating as they should). Morgan asked about your cam, as the more radical the cam, the stiffer the springs have to be to keep the lifter on the lobe. Luckily for you it is a hydraulic cam, so the maximum open pressure is not nearly as high as encountered with a really high reving solid cam. If you have a set of old worn out stock springs the chance of a cam lobe wiping would be reduced by replacing the springs with your worn out ones.
I used to remove the outer springs and run my cams only using the inners which reduced the pressure on the lobe and bottom of the lifter. You need to keep reving it up and letting it fall back to a slower RPM to get oil splashed on the cam and reduce speed top keep from wiping it all off quickly.
After a half hour to forty or so minutes the lobes are worn in enough to shut it down and drain out most of the iron filings that you produced by rubbing the metal together to allow the softer lobe to wear into the harder lifter. If you think that first oil change gets rid of all of the metal, replace your stock drain plug with a magnetic one. Next oil change you might be amazed to see all of the metal it attracted.
By the way I built motors in the old days before ZDDP went away, and I still occasionally wiped cam lobes. GM EOS added to the oil is a good insurance policy.
If you can afford it now would be the time to upgrade to a roller lifter engine; before you fill it with cam lobe filings. Roller camed motors need no break in period as the rings seat within minutes if you honed the cylinders with a head plate, and there is no break in for the lifters.