Your 1966 Lightning would originally have been fitted with a pair of 1 5/32 inch monoblocs.
The later Lightnings were fitted with a pair of 30 mm concentrics.
Your 300 and 301 carbs are "generic" 32 mm concentrics recent pattern. I presume they are standard ones rather than the premier version with the upgraded idling system
I think you will have to experiment to get the carb settings correct because of the non standard size carbs, but suggest that you start with the jetting for the A65 Spitfire MK3 which also had 32 mm concentrics.
Spitfire specs were 190 mains, 107 needle jets and needle in position 2. The pilot jet in your carb would have been a pressed in pilot bush.
There is a lot of information available on the Amal website. Worth viewing.
This link takes you to the standard spec for 932/300 supplied by Amal.
http://amalcarb.co.uk/mk-i-concentric-series/900-series/base-line-specifications/32mm-bore/rh-32mm-4-stroke-mk-i-carburettor.html