The SU in the photos looks like a type "UBA", as fitted to late Morris Minors and Morris 8's in the thirties. The "OM" has a stub pipe on the inlet side rather than a flange. UBAs are generally stamped "1930" on the side (nothing to do with the date).
I use one of these on my Chummy with a manifold I made from copper pipe, silver soldered together. In the sixties, V W Derrington made a cast aluminium inlet manifold for this job, it has to be very compact to get the SU under the bonnet without a side bulge. I have one of the Derrington manifolds but it's cracked.
I'm waiting to see if I can get it repaired or whether I can find a foundry that could cast a small number, so that they could be reproduced.
BTW, the manifold in the photo is upside down
I use one of these on my Chummy with a manifold I made from copper pipe, silver soldered together. In the sixties, V W Derrington made a cast aluminium inlet manifold for this job, it has to be very compact to get the SU under the bonnet without a side bulge. I have one of the Derrington manifolds but it's cracked.
I'm waiting to see if I can get it repaired or whether I can find a foundry that could cast a small number, so that they could be reproduced.
BTW, the manifold in the photo is upside down