Is there other brass that can be used, case formed, ect in place of original 303 brass

My first choice would be 30/40 brass. In fact I have heard that some rifles will accept either
one.
Good luck!

No. Other than Japanese 7.7mmR which is the same thing. Or, possibly, a .410 brass shotshell. But it would not be safe at the head area.

About 15 to 20 years ago Remington .30-40 Krag brass was .455 head diameter and made better brass than original .303 brass. Now they are the same diameter.
I have also made .303 brass out of .444 Marlin brass but it is hard work. The head has to be swaged from .464 down to .458 or .459. with heavy duty dies and a heavy duty press. Way too much work but the brass lasts a lot longer.