Take a look at the HastyBake. I have one that's about 5 or 6 years old and
aside from a couple of external spots were the powder coat burned off, rust
free!

The firebox can be lowered and raised by operating an external crank. The
gives instant control of the temp. The design is robust and trouble free

A HastyBake can obtain a grill temp of 600+ degrees (depends on the lump you
are using) and will smoke at 200 for hours. Expensive yes but a unique and
excellent device.
..
The only thing that get's hotter is my TEC infra-red grill. Aside from
searing and broiling the TEC is hopeless.

Richard Smith