I'm making a timber top for my garage cabinet (indoor motor workshop). I need a timber size of 495 x 73 x 20 mm thick. I plan to buy it pre-cut from Carba-Tec Perth. I have a few questions about timber selection:

Among other things, I'll be banging, cutting and sawing stuff on it. In this case, is treated or untreated timber recommended?

I'd like to use jarrah for its hardness but they're generally not smooth (knots and veins). Do you recommend any other timber?

Thank you.