OR you don't need any modifications at all. I see you have purchased the Gourmet model. That's the exact same one I started with. There is a center hole at the bottom of the charcoal pan (air intake). Keep it open during your smokes. I took a long metal skewer and bent the end 90 degrees and about 4 inches long to reach under it and clear any ash accumulation. Also, on those smokers, it helps to have a shield for wind.
I made some really good BBQ with mine, it was a great learning experience.
Good luck on your new rig and the main thing is to have fun with it.
Weber WSM, Weber GA, Weber Spirit S-320
Charbroil Oilless Turkey Fryer
Wife LuzziAnn 1956 model.
Maverick ET-732, Superfast LSU Purple Thermapen & ThermaPop, Party Q