Well, the Bratton's catalog lists '28/'29 and a different PN for '30/'31 for their trunk lids, so they might be different. Give them a call.
The shape of the later turtle deck (along with the quarter panels) is different on roadsters. It is hardly noticeable but they are different.
There is a difference in the inner at the top where the rumble latch goes. 30-31's will fit on a 28-29, but the other way around MIGHT have some interference issues. I've never tried fitting a 28-29 to a 30-31 so I don't know for sure, but it looks like it would be close.
I was riding with a friend who wanted to stop at an antique store near Jefferson Texas. I told him,I betcha theres Model A parts here. Sure enough I found a Model A wire wheel and a deck lid. The guy wanted $10 for the deck lid!