That's going to be tough.
I'd suggest first calling Marlin to see what versions will fit a model that old.
Better to spend a phone call then blow money on a bolt that can't be used.
I'd suspect that Marlin might be the best bet to have a new bolt fitted, and possibly, they might have compatible bolts.
Wisner's has some good pictures of Marlin bolts through the years, so that may be a help:
http://www.wisnersinc.com/additional...ARF_rifles.htm
(Down the page).
In those days, bolts were at least partially fitted, so you may need pro help installing one even if you can find one that's compatible.
Here's some possible sources for older bolts. Gun Parts is out of stock.
http://www.poppertsgunparts.com/cgi-...a_gunparts.cgi
http://www.wisnersinc.com/rifles/marlin/rflever.htm
(No bolts listed but they might have one)