Like Pete said the horizontal CC would be fine using that. But I now have the FB and cabinet above the FB made from flat plate, and I can put a lot more in a square box than I can in a round one.
Making memories!
Current Smokers: Backyard RF Offset and Hybrid RF Offset trailer rig with Cowboy cooker and fish fryer, always room for more........
Have you looked at the plans on smokerplans.net. There's several sets of plans on there that use 24'' pipe, it's hard to beat a good set of plans. If you want to design your own, then you should check out the pit calculator and look through the RF builds and get some ideas.
Another awesome build begins. We always build and enjoy and then at the end of the day we say ..... dang it I forgot to take pics. Just saying. It happens.
Forty is right. You won't regret building a reverse flow if you use the calculators to get the dimensions right. Mine was made from a 100lb propane tank with a square FB and Warming Cabinet above. My only regret is that it is too small. Now I'll just have to build bigger one.
If you have any specific questions going forward, just ask. There are lots of experts around here who are glad to help.