Registering interest now.
there is a certain sigma dizzy that can be modded to fit, cant remember what series of sigma, but its a elec of a 2.6 astron.
Runs the same style of inside parts as the series 2 bluey dizzy, but they run in the oppisite direction from memory.
Will also have to adap a mount to bolt up to where the existing ca18 CAS went.

Webber manifold are available, but uber rare :(
I have one of these, it was the first one seen in years of hunting down ca18 bits in japan.

40's or 45's will be fine.
get some huge cams ground up, use ca16de pistons for higher compression.

Tuf110, im interested to see how and what youve mounted them bike carbs too, I assume they are softmounted, but to what?
modified standard ca18 butterfly manifold peice?