All the more reason to proceed with moderate loads. Randy gives good advice. Maybe another member your area could help with inspection.
Good luck.

Joe,
Here is Parker recommended load data for your 12 gauge.
Good shooting.

While the outside appearance of your gun being original may lead you to believe the barrels have not been altered that is not always the case. I would urge you to consider having the barrels measured. I see that you are from the St. Charles, MO area so maybe a member can reply with information on a gunsmith in your area that could measure your bores. You might also consider going to the home page and looking in the Parker FAQ's section and then search under "need a gunsmith" which is a section devoted to gunsmiths the members have used and would recommend. You might find someone there.

I have looked through that gunsmith section a couple times now, no one near St Charles MO, that I have seen.... What measurements are you concerned with?

Chamber length, bore diameters, minimum wall thickness measurements (MWT) at juncture of forcing cones and end of chamber, MWT at end of forcing cone, MWT at 9" from breech, and also the MWT at any spot forward of the measurement taken at 9" from the breech. You may want to search the forum Joe as there has been a lot of conversation on this topic over the years.

Chambers as measured them are 2 5/8th it appears. Not 2 3/4" like my Ithaca NID. I could be off by that 1/16th, but measurement I got was 2 5/8th.

It was my understanding, Trojans had 2 5/8th or 2 9/16th chambers, yet are fine to shoot 2 3/4" shells.

Yes, the 2 5/8" chamber length is fine for 2 3/4" ammo.

Barrel wall thickness at the points Randy indicated would be my primary concern to know before shooting any of these old guns with any load. A lot can and often does happen to them in a hundred years or more.
A $100 Manson gauge is a great investment if you can't find anyone nearby that is qualified to make the measurements for you. Lots of info on the site on the best way to use one. Best investment for safety and peace of mind IMHO.

I don't know where this notion started that larger and faster loads are better. I grew up in a fishing village of subsistence living. Preferred shells were low-base 1 1/8 because of cost. I doubt those gunners, mostly relatives and all of them poachers at one time or another, knew their shells were making better patterns than the more expensive "high brass."

I didn't know myself until I started competitive shooting in the big city. Consider, too, these fishermen could shoot, knew their limits, no iffy shots, always retrieved what they hit regardless of the time it took from a hunt, and their waterfowl were the heaviest kind from harbours and tubs at sea. A lot of what I see today sickens me.

I agree, but as with most things this day, faster = better.

Would love to find just nice shooting 1 1/8 oz 1200 fps loads, that I didn't have to reload myself. You can find em in target loads. I use the Herters low recoil target loads for busting clays all the time.

But finding #6 or #5 hunting loads that are low pressure, and 1200 mv or less is hard, RST is about the only place for those, and by the time you pay shipping, they are not cheap..... Although, it's the route I go unless I load my own.