Aveling E Type Governor valve arrangement

[113043]

I am looking to find what sort of governor valve should be fitted to an E Type Aveling. The ports are bored 2 1/4" diameter, but appear to already be bushed. I would have thought a 1 3/4" diameter valve should be fitted with bushes to suit.?? usual size for this sized engine bore and stroke.

Any one got a drawing or any experience of what the arrangement is or should be?

many thanks

JW