I have the same problem with my 1930 H3.
When I got the bike, it had only a few original engine parts left.
With these parts came 2 different Valve Covers.
I believe the slotted one (it is casted alloy) is the right one for the year.
The front is slotted, It is only on one side closed,the other side is open. May be it is modified?
I think the B29 has the same covers.
Michael