Take a look at the thread I did on the Red Weber rescue, that one is pretty harsh, but as long as you don't care that it won't be perfect it can clean up OK. I really prefer the old style bottom daisy wheel kettles.
Dupli-Color Engine RED is the closest match I've found. I'd drill out the rivet on the top vent and mask off the rusted/chipped areas as close to the edge of the remaining porcelain as possible and paint the chipped spots, let it dry and paint again, building up the layers. None of mine have been THAT bad but one can of paint and a chitload of masking tape will do the job.
I had kind of an assembly line going and rehabbed 4 REDS this shot, and did a couple before and have two more waiting in the wings.
It's kinda bizarre the lengths I've gone to keep these out of the landfill, all of these were freebies, which I flip and keep the Master-Touches for myself to use on the drums and for a comp kettle.
After I've got a few coats of paint on them, I remove the tape and use a razor scraper to blend the masked paint into the chip, use fine steel wool to get overspray off and use Meguiars "Mirror Glaze" #7 sealer and buff with a cotton rag-the color just pops right out!
I wouldn't waste the money to powder coat one, TVWBB did a RED WSM and it was reported to have turned orange over time.
REDS RAWK!!