If you are a competent arc welder then these chassis can be built easily with a small arc welder,this has been argued many times on this forum,and as I have said before:the time it takes to fill a gas bottle,well the whole chassis could have been cleaned and wire brushed in that time,and the interest and the gas on the cost of a MIG would pay for all the rods ,hacksaw blades and grinding discs etc.
Also you could buy if available 1.8 or 2mm steel,also I have seen recently 14 swg rods and16 swg rods.30 odd years ago I welded up panel steel converting a car to a ute.the rods in those days were called "mirrorcraft and satincraft".
However I am a lone voice here and if you are in a hurry then you may be better of with Mig with gas .
Note that I say "competent arc welders"which means "the ability to arc weld in all positions".Yes that takes some practice.
You will also have at the end of the project a welder that can be used cheaply and easily on a large steel yacht or launch etc if you wish to go on to go on to greater things.
And I am not impressed with much of the Mig welding I have seen .
If you wish to be a good MIG welder get Richard Finches latest book on welding.Mig welding is more complex than you may realize and most Mig welders seem to reach a certain half way level of competence and then they dont proceed much further when with some study onthe subject they could improve considerably.David:eek: