My roadster has domed pistons, a cross-flow head and twin Solex carburetors on a CTA twin manifold.
back in 2012 I visited an engine tuning specialist in Blackpool as I was concerned that the jetting on the carburetors may have been wrong.
The car went onto a dynamometer(?) with an exhaust sampler.
There was little or nothing that was changed, original jets retained, my recollection was that the calculation of the power to the front wheels was 65BHP.
Has anyone else any figures to report?