I will say this and then you will do what you want.
The margin for error breaking in a cam is very narrow. Anything you can do to get the window open wider is cheap and easy.
Spring pressures, even as low as yours are are not the only consideration.
It doesn’t take long to remove the inners (or not put them in when the heads are going together) and it takes maybe an hour to install them after break in.
There is a reason why guys use lower ratio rockers, take the inners out and go through all the machinations they do to stack the odd in their favor.
You can do everything right and still lose a lobe. Maybe the lifter bore is on the loose side and any extra spring load may inhibit the lifter from rotating. And if that happens it will damn sure go flat.
You are working with 45-50 year old blocks. They move around. Unless you are bushing the lifter bores you are dealing with what you have. They may not be (and probably aren’t) in perfect shape, let alone being on the low side of tolerance.
You are closing the widow tighter by not removing the inners.
Saying if the cam goes flat means it was junk to begin with is very myopic. Yes, it happens. But skipping a simple process to add to the likelihood of success is bad policy.
