I can only tell you what I know, namely, the only way you are going to be able to get any brass is to form it from the 220 Swift - and good luck!
As for load data, this si what I have:
From the Completely Revised 4th edition "Cartridges of the World" By Frank C. Barns Edited by Ken Warner, page 90.
75 gr. 3031 37 3,300 1,800
100 4895 34 2,680 1,595
112 3031 30 2,650
112 4895 34 2,670
112 FL 2,560 1,635 200yd MRT=3.5"
Primer.....= Large rifle .210
Base Dia. =.445
I do not if this is IMR or Hodgden powders. Likewise primers, etc - I simply do not know and the data does not give this info.
Also, I just found this on another site, may be worth a look:"Buffalo Arms has brass and dies. I have been meaning to reload myself, but havn't had the time to research the loads. Any load data would be helpful. www.buffaloarms.com "
And finally, yet another:
"You can easily make brass from .220 Swift cases. Many years ago I had a Winchester Lee-Navy rifle. You may (or may not) need to slightly reduce the diameter of the .220 Swift rim. I do not remember the details, but I made brass without any special machine tools or reloading dies and it worked fine. I probably used a .243 Winchester or 6 MM Remington sizing die to expand and neck size the brass and the corresponding seater die to seat the bullets. I remember shooting a ground hog with a 60 or 75 grain hollow point bullet. It worked great. I sometimes wish I had the rifle back. Good luck"
And so, I am dry of info. Good luck with the project, sounds like fun and I wish I were there to help you, I could at least fire up the coffee.
Best wishes and Merry Christmas!