oldbiker, I have had bikes with 35mm forks with a 34mm fork guard, without the stays, on them so im sure they interchange.
There was a thread about this and the thought was the 35mm fork guard mount is different from the 34mm so i measured and took some pics. The 34mm guard mounts are cast into the fork legs and the 35mm seem to be welded on after and the 34mm mounts have more meat around the bolt hole.
Some pics i took.
1; 34mm
2; 34mm, 60mm center to center.
3; 34mm, 80mm outside to outside.
4; 34mm side view shows the cast mark
I have mikes fork brace and it will mount to the 34mm forks but the extra width of the 34mm mounts you may have to shave a bit from the outside of the mount, the brace fits one way but the mount catches when i turn the brace around. Obviously it is an engineering difference on the brace.
5; 35mm, 60mm center to center.
6; 35mm, 75mm outside to outside.
7; 35mm, side view shows no cast mark on the guard mount but it does on the caliper mount