The only factor that you should keep in mind is the steel type you choose. Jeffrey Knight uses leaf springs from semi-trucks for most of his tools. One aspect of using top tools in larger pieces is the occasion when the punch or chisel gets stuck. Trust me, it will happen. There are several approaches to solving this dilemma, one is to keep some powdered coal or coal dust near the anvil.
Carbon is an excellent high temperature lubricant and coal dust is mostly carbon.
I you briefly we the tool and then dredge it through a can of coal dust, enough will stick to lubricate the tool and allow free removal. The other option is to sprinkle a little dust or even small coal nuggets, directly into the whole. I don't find this to work as well or as quickly. If the tool gets stuck anyway you will have to free it by either tapping it out, a brass hammer is handy for this, popping it out by flipping the work piece over and giving it a sharp rap on the anvil with the tool overhanging the edge. Or last but not least is prying it out with a knuckle buster tool similar to what mechanics use to spread ball-joints.