Does it matter my exhaust manifold clamps are not flat two are and two wobble. On my 1924 model t roadster.
It shouldn't matter as long as they clamp. Check that the bolts are not reaching the bottom of their threads in the block before they clamp.
If one does bottom, you could fit a washer under the head.
They don't wobble when you tighten the nuts, do they?
When tightened they should clamp both the exhaust manifold and the intake manifold so the manifolds sit tight and seal to the block.
Esthetics may also matter - other manifold clamps are not so hard to find.