I recently smoked a large "london broil" (round steak mostly). Not the tastiest cut. Definitely requires marinating at least 24 hrs but can stand more. It's a very lean cut, thus easy to overcook, especially on a charcoal fire with hardwood charcoal.
For the last one, I put both piece thick end towards the fire which was on the opposite side and down low, nearly to the bottom. A few chunks of pecan made prodiginous amounts of smoke. I used a remote thermometer. As soon as the middle hit 125F, I removed, raked the fire out a bit, faned it, then seared each side close for about a minute. Then off-grill to a wire rack.
Next, grill some bread until well marked.
Raked fire evenly across, then dropped fire box to the bottom, laid down 1-1/2#'s of bacon to pecan smoke as the fire died down. Hasty-bacon goes well with everything. I lucked out as I found nice, thick bacon for only $4/#.
Why leave without it?