OK,
Q:"Can the Pro-Series, Pro-Billet, Ready-to-run, be retro-fitted, back to a regular electronic ignition without cdi function?"
A: Yes. The "regular" ignition module can be swapped in place of the ready-to-run board.
TSP-JM6919 Ignition Distributor Magnetic Pickup for 6600 & 7600 series Distributors
these are also interchangable with the MSD 84661
Distributor Magnetic Pickup MSD Ignition 84661 - Pace Performance Parts
There are a few big block ready-to-run pro series, pro billets, that don't have a "regular" version. this applies to them too.
Just don't confuse the names.lol which i sometimes do.