k-frame strengthening
And just a note from the cheap seats: Use a tig welder if you can versus a mig. Mig welders, especially without the gas attachment, introduce a LOT of air which heats up and can blow right through your powder and look like a volcano field if the proper steps aren't taken in advance. I assume you've checked your guy's references already and have seen his work for yourself.
Good luck! Post up some pics when you get it back.