How good can lifter bores be after 50 years. And how long was that side run with no oiling.
Using a home kit will resize the lifter bore. but will it tru it to the location where it should be. The main reason you tru a lifter bore is not only to correct the diameter. But to put it in its proper location for performance. If you would ever see how far they are out of place your eyes would bug out.
That is why there is a fixture for the cam tunnel and one for the deck. Mopar and Ford are the worse. The fixture locates them them from front to rear and puts them at the proper angle. You can't screw up this way.
A CNC program is only as good as the person placing the block
And the tube in the block? I would have it remove at a machine shop with a reamer. That is what my son said he would recommend so your starting fresh. Then bush the lifter bores so they don't leak down around the diameter. My son just got a set of lifters for a big block ford. There was three different Diameters in one box. With no wear in the bore the smallest one just makes spec. This block is also 50 years old and there is plenty of wear.
Oppinions are like *** holes everyone has one including me. Take this advise and use it how you want. Usually when Hyd. lifters clatter it is from the bore to big.
Here is a video of a standard size of original bore reamer marks part way in the bore, front to back showing how far off the lifter bore was at an angle
How the fixture works with the tooling. There is no way to be more precise To locate the bores. look how the reamer is held top and bottom by bars. Locating the bore is precise no Human or Computer error can be added.