Just an air leak that is keeping you from running. That is why it is lean.
SAE30 is Nd30 same thing. Has has has to be non detergent or else it will melt all your rubber clutches.
No the head does not need a gasket as the head has a lip that goes into a groove on the cyl. But I do like a head gasket all the same.
Be sure your carb has the rubber O-ring in it. Then the shim goes in, then attach to the intake. No O-ring = airleak on the sha. Also be sure you are using the stock air box on there it needs the restriction. Unless you upjetted like 3 or 4 sizes. But with the forward facing carb you should run a box for sure.
Most old garelli airboxes have some nice tuning ability to them. You can pull out the tubes for better air flow, I have even added a few air holes as needed. You can always plug them back up.