2" Aluminum Weldment looking for advise on Equipment

[Portable Welder]

I have the Cobra Mig 260 Push Pull system which is from MK products,Its approximately a 2003 model.

I just quoted a big aluminum job to weld 2" thick aluminum plate together with several ribs to be welded under the plate that are 3/4" thick x 14" tall.

Ive been looking at the welder that OTC offers that does pulse mig but isn't a single phase machine, so now I've been looking at the miller.

Miller has the 350 MPA and the MM 350 pulse, I just wonder how they will stack up to the Cobra that I already have.

The fact that the miller machine puts out more power should help for cooking into the 2" aluminum plate where my 260 amp machine is going to require a ton of pre heat.

So who has used both and is there a big difference between the Cobra verses the Miller

And who has used the 2 millers, The 350 P verses the 350 MPA.