I am not really a firm believer in running long inlet trackts, so on mine I just have a thick (3mm) soft gasket between head and shield.
In your case I'd use a thin gasket, then the spacer, another thin gasket, drip shield, carb.
When tightening, I put .003 feeler strips between carb body and drip shield left and right, tighten the nuts until both strips can be pulled out with equal force, and then give both nuts an extra 1/4 turn.