What’s the current status of the GRO tanks fitted as standard to Bultacos , OK for road use in the UK ?

Yes

Thanks 👍 I was repairing my 116 tank when it suddenly occurred to me that I might not be able to road register it when I’ve finished the restoration with the original tank .

1 hour ago, Lee halsall said:

Thanks 👍 I was repairing my 116 tank when it suddenly occurred to me that I might not be able to road register it when I’ve finished the restoration with the original tank .

The DVLA inspection for registration, if they ask for one as they don't in every case, doesn't look for things like that, it's really to ensure you're actually registering what you say you are, chassis number check etc. and not to check RTA conformities. I don't know if the law from 1973 is still in force and I think it was to actually prevent new machines being sold with glass tanks, as there were still bikes being used on the road back then with glass tanks. There are plenty of bikes in use now with glass tanks

So, Woody while your here , what about tyres . The Alpina had mx tyres  supplied from new,  and I have a pair of Michelin enduro tyres going spare . If I can register it as a 1974 , will I-need to get an mot before registration ? Ifnot I can use the enduro tyres . Had a bit of a heated discussion when getting my PE first tested  due to the enduro tyres that were fitted .

You can only use road legal enduro tyres on the road - they are marked with the E mark in a circle. If they don't have that they aren't legal for road use.  You won't need an MOT to register it on a 74 plate, nor insurance.