I noticed that the TUHS archive does not include a 4.1BSD distribution.
Also, while poking around the net, I've found a number of purported
tape images of 4.1BSD dated 7/10/1981 that look to me to a little sketchy,
since most contain files dated well into 1982.
So it appears to me that 4.1BSD is semi-lost.
While googling all this, I discovered that the School of Computer Science
and Statistics at Trinity College Dublin has an online archive catalog
which lists a couple of 4.1BSD distribution tapes in the "John Gabriel Byrne
Computer Science Collection".
https://scss.tcd.ie/SCSSTreasuresCatalog/
Perhaps someone from TUHS who lives near Dublin could investigate and
see if images can be made of these tapes?