Just to close out this thread, finally got my hands on a chassis. Every measurement I've taken so far matches up with the Austin. Calibratied eyeball still working! Early 30s cars do seem very similar. Only downside is an ape fitted the wrong rear top arms- literaly using a club hammer and chisel! Rear camber is probably 20degrees!
Not a great problem as the shock towers are where the back seats fall. Will probably go inboard horizontal shocks.
I'll start a new build thread as this is now the wrong section to continue in.