First what is your pressure goal? 5,000/1 ounce, 6,000/1 ounce or 7,000/1 ounce. Second what hulls do you have to work with. Third what wads, primers and powder. Once you give someone those inputs they might be able to get you into loads you can use. What you listed is not a great combination, workable, but not great. Then load up and have them pressure tested. Never trust information freely given over the internet. A single minor mistake could be a real issue.
I have over 30 powders, seven different types of primers, a pickup load of different wads, tens of thousands of hulls in everything from 10 to .410 and years of accumulated reloading manuals and recorded data and I still trust, but verify, by having "real" new stuff not tested by a known source tester. Printed stuff, from decades ago I take with a small grain of salt and anything off the internet with a small bolder of salt. In honesty, I have taken loads for 2 3/4" and loaded in 2 1/2" using roll crimps with fairly good results but that is not really very safe.
Thinking out loud, have you looked at some of the straight walled euro hulls or Federal hulls? They are cheap, or free for pickup, at most shooting ranges. Straight wall is a bit easier to find low pressure loads for than a tapered hull like STS or AA hulls. Get a large number of them first. Then start doing your load research. Find one and then let it become your default low pressure loads. I would also look at a Federal Hull trimmed down to 2 1/2", with AA wad and Clay's powder. Load up six of them and send them out to test. Once you have found what you want load only that load in that hull so from that day forwards you will know every hull loaded of that type is a low pressure load, safe in all your guns.
