It's a good idea to have them tured up to make sure they are flat and smooth. Decking, I'd be leary about on these motors.

And along with the Eastwood or Mr Gasket porting kit, get a good set or carbide bits also along with some buffs...

I ordered this kit for mine along with a set of carbide bits off amazon, the buffs give your ports that shine..

Standard Abrasives, Deluxe Head Port & Polishing Kit - Competition Products