I have an 20+ year old Meco vertical that I just cant get hot enough. (Bad pic of it, sorry)
I vented the top, sealed the big front slider door, put an apron with air intake around the bottom. I use foil as a lid gasket for now.
The fire-pan sat on brackets inside, removed those and gave the pan legs so to lift the smoker off it. I added a grate and drilled several vent holes. Use Royal Oak lump for fuel.
Still, it won't get above 200, usually sits at 180.
So I'm thinking of drilling 1/2" holes very close together (like swiss cheese) in the flat part bottom of the pan, and where I can under the grate, then hang an ash catch pan under it. I think this will give the fire more air. Also I will probably add another intake or two with regulators at the bottom. Don't know if they are needed, but I think they will look cool
This is a better pic, before I fixed the front slider door.