I have never used SMBC and tomorrow I will try if for the first time. I don't know if I can make a dam for the filling with chocolate SMBC or it has to be a crusting BC?
Thank you!

I never use a crusting buttercream, and most often use a meringue-based bc, and always create a dam for my soft fillings with these buttercreams successfully.

You can pipe a dam with regular SMBC and put it in the refrigerator to firm up.