I've noticed a couple things about "Speedway", they've got a beautiful catalog, but they don't go into much detail about what their item does, or doesn't include. I presume, that they assume, that you know exactly what you need and nothing more.
On the other hand, there are other suppliers that go to the other extreme. I've found suppliers like Classic Parts of America (as well as others)that are more user friendly, and have a detailed description of what is included with the component you are ordering.
As an example, the above mentioned supplier offers a "Valve cover stud kit" which includes all the little stuff you're going to need to install your 2 hole valve cover on a 235. It is part #86-105A @$11.95 USD.
The Offenhauser cover you received, is the standard cover offered by most suppliers. However, to get the cover to seal properly, you're going to need a spacer that moves the thermostat housing out 1/4". The cast valve covers seal well, but protrude outside the normal steel cover sealing area. Langdon Stovebolt Engine Co. is sold out of the 1/4" spacer@$15. USD but has a 5/8" that is drilled and tapped for applications that use water heat to warm the intake. ($25.)
To the best of my knowledge, there are currently no cast aluminum covers with the stock arrangement of 4 holes being offered for the 235. I hope this helps!