I did not see any 7mm rimmed brass available, so I got to looking at what was close.
303 is very close. The rim is a bit larger diameter by .009". That is ok for me as I will be using a lathe to cut the rim rebate in barrel breach.
The base is .014" too small but a piece of cellophane tape around it would center for the forming shot.
The case is .022 too short but will stretch a bit when necked down and that little short will be just fine with me.
What do you think?