set of 6 AC type G spark plugs for 1929 std Buick

Looking for a set of unused or lightly used AC type G metric-thread plugs for 1929 Buick.

Any particular reason you would go used plugs and that particular make ?

According to an AC chart available from the 29buick.ca web site, AC was the original supplier. I have Champion plugs now and don't know what p/n they are. I am having some odd behavior with my engine and would like to do a couple of things:

1) Figure out what is wrong, and fix the issue

2) Learn more about how this car works, and what effect various components have on performance

I can ask for opinions on the problem and I will receive several different ideas; ultimately I have to figure out what the problem is myself. So my approach is to get a few spare components and swap them out to see what effect they have. Spark plugs are one issue because I've heard and read about the difference between older "hot" plugs and more modern ones that do not operate as hot. Spark plugs are easy and relatively inexpensive to replace, so that is one good place to start.

I don't know if NOS AC type G plugs or a new equivalent are available, so I am willing to try a lightly used set if I can find some.