I think you're going to struggle with the 'traditional' Scottish quilt as a concept as there really isn't any that I'm aware of. I found a couple of tartan Cathedral Windows blocks
here (you have to search 'plaid', lol).
Alternatively, you could think about making several Saltire blocks, perhaps as part of the border/back.
If you like to appliqué, then a thistle might work too.
There is a block called 'The Scottish Cross' - found
here - but I've no idea of it's provenance with regard to actually being Scottish!
Good luck!