Oh, no problem, I completely took it as that, a great suggestion which given the means availability would probably be the best way to resolve this issue.

For now I'm going to cross my fingers and give the Dorman plugs a try. Co-incidentally I found a Mopar specific "Rocker Arm Shaft Plug" in their catalog, but that is a #555-067, which is listed as 39/64" diameter...and that is simply too big for my MP shafts.

I've attached the PDF catalogs, both the Make specific stuff and the MISC section.