I'm not sure if you got an answer yet, but I don't think you should be able to use a square bore spacer on a spread bore intake. The bolt holes shouldn't line up.
You may be confusing a 4 hole spacer with an open spacer. The square bore 4 hole spacer will have 4 eqaul sized holes to match the carb. The open spacer will have one large hole.
The spread bore would have 2 small hole and 2 large holes.
You will need to run a spreadbore spacer with a spread bore carb.
Generally you use an open spacer for single plane intakes and 4 hole spacers for dual plane intakes. Sometimes if your running a single plane and it doesn't truly match the rest of your combo you can run a 4 hole spacer to help out the bottom end, but thats a crutch.
I hope this helps, if I read your post correctly.