For a few dollars in plumbing parts and a mig tip, you could make a nice burner that'd work great. The forced air/propane setup would be more efficient. If you're talking about the little mapp torch, you'll be disappointed with that size forge.
My first forge, which I still use for little stuff and heat treating, is a hollowed out kiln insulating brick with a hobby torch. Works really well until you get into big or thick blades, then it takes forever to bring 'em up to working heat. Isn't any good for forge-welding though.