The one that I use is not entirely practical Grant - it's a round muffler, about 10" diameter and about the same in length, that I picked up from the local shop. I just asked the guy if he could give me a good condition muffler with one ended swaged to fit over a 1 1/2" stub. Don't know what car it was from but it really shuts the pony up. I only sit it on there (vertically) while I'm starting, and then I take it off and throw it in the box.
However, I'd say anything, including the drilled tube approach would be better than nothing, but if I was to choose the ideal muffler it would be maybe a 5 inch diameter and about the same length glass pack. A straight-through resonator will work some but not as well as a muffler and they tend to be a lot longer. Stainless glasspack would be good for longevity but stainless does tend to deliver a bit more of a "crisp" note than aluminized steel