Dave,
I don't think I'm familiar with Chris G's recipe, so I can't directly comment on that. If you have a link to it, it may be helpful to provide it.
Temp-wise, if you want to cook on the bottom rack, then, yes, you're probably in the ballpark if lid temps are about 225. I don't see why you couldn't cook it on the top rack, especially if you have nothing else in the smoker. Cooking it on the top rack will also make it easier to check on. Personally , I would go a little higher like 235 if I was going the low and slow method, but the lower temp may be for the foiling that Chris recommends. The distance between the 2 racks shouldn't make any difference in the finished product. As far as being "ready for supper tonight", that depends. A brisket is done when it's done. A 9.5 pounder should be done by about 6 - 6:30 especially if you plan to foil it for 4 hours. The foiling should speed things up. If you have a thermometer, keep an eye on the internal temp; check the temp in the flat (flat being somewhat rectangular end as opposed to the rounded end) not the point. When the meat gets to about 185, it should be done, BUT and it's a big BUT, you need to check for tenderness. Temps don't matter if the meat is still tough. Using a probe, fork, etc., poke the flat. If if goes in like a hot knife into butter; your brisket is done. If there's resistance, let it cook a little longer (10 mins) then check again. A jello-like jiggle also is a good indicator that the brisket is done. Don't keep it on the smoker if it's done; you'll only dry out the meat. Wrap it in foil for at least 15 mins then slice and serve. Let us know how it's going.
Paul