You’ll have to decide if you really need the added trouble and expense to o-ring the heads/block to use copper gaskets on a low output 2bbl 9:1 build.

If you deem it necessary, you can o-ring either. Many machine shops can cut o-ring grooves in a block with their boring machines.
Most can’t do it to the heads.
Which way you go might be decided by what you can get done locally.

I can’t imagine any scenario where I would go to that trouble for that build.