Well I have a m1 single plane on a 69 charger and can not use any spacer under the carb it's to close the hood.
I had to order a 1.5" drop base and use a 1.5" filter to with KN extreme top to make it just barely fit under a stock hood and have a air cleaner on it.
Also tried a 1/2" spacer under carb hood would hit vent tubes, this is with 850 Mighty Demon Carb.
The SD is more like a Torquer height so you should be able to use a 1/2" to 1" spacer most i have seen do.