LA3 states that you cannot certify a modification under that code if it causes the vehicle not to meet the required gaseous emission standards. It goes on to say "Vehicles manufactured on or after 1 January 1969 and prior to 1 July 1988 need to comply with the Second Edition ADRs..."

So you need to comply with the emissions testing as per much more modern EFI vehicles from the post 1986 change to ULP, which were almost universally EFI to meet the emissions standards of the day. You will need a cat and you will need very good NOx control at idle and absolutely perfect progression tuning. To get it to pass at idle will make it dangerously lean and run like a dog on the primary channel, and probably also the secondaries. It will be all but impossible to do it with a carby.