Hi Brist,
Yes,if it was me I would give the walls a damp down, coat it out with Browning, followed by multi-finish.Or would that combination be too thick. say,3/8"ish? Alternativly,if the breeze blocks are tidily built,what about trying 2 or 3 coats of multi on it's own.Never tried that on a whole breeze wall before,,but I think once you had a good first coat on,and steadied up a bit,another good coat on top of that,maybe 2 and trowelled up, 1/4"thick or less overall,i'm sure it would work no problem.Years ago when plastering window reveals (no beadings) just pieces of wood nailed around the window,we would plaster straight onto the breeze blocks with board finish,with no problems at all.That is why I'm sure it would work with multi-finish on your job.
Regards:Roughcaster.