Stainless steel will reflect heat if the surface is polished. With a mat black finish most heat will be absorbed. A polished surface on the other side of the stainless steel sheet will give a low coefficient of radiant heat transfer. But it's unlikely you can keep these surfaces highly polished. If not polished, the stainless steel sheet or plate will absorb heat on one surface, conduct it to the other surface, and emit it on the other side It will provide some shielding, however. It might work just fine. Asbestos sheet absorbs heat on the hot side, but it has a very low conductivity. This means that onside could be very hot, and the other would be much less hot much less hot. The less hot surface, toward the engine, would give off much less radiant heat than the hotter stainless steel. In this application there is little danger from the asbestos. However, the asbestos sheet is more likely to deteriorate over time. Mine looks a little raggy on one surface, but it's still intact. I hope this helps, and if you go with the stainless steel I'd be interested in how it performs. A thermocouple temperature indicator used on the engine facing side of the middle of the shield will indicate it's performance versus an asbestos sheet heat shield, the lower temperature being the best heat shield. Warm up the engine then let it idle for 15 minutes before taking the temperature.