I had to modify some machine screws to get the adapter and spacer bolted to the intake. Those two spacers actually bolt down first, then the carb is bolted to some studs in the top of the adapter.
Here are the screws I modified. These were 5/16-18 x 2 1/2" long screws.

I had to shorten them to 2 1/4" long and turn the heads down to .500 from .580 so they would fit the counterbored holes in the top of the adapter.
This is how they sit in the adapter.

These screws use the original carb bolt pattern to bolt the spacers to the intake. The carb then attaches with the studs you see in the pic.