i use a weld pack 100 and .025 wire with gas i like the .025 wire better than the .030 wire. it just flows better for me and i dont have to turn the gas up as much.
but i over weld everything. in the pictures attached the shock tower is 3/16 and the zuk frame i think it is less than 1/8. it is offset and i weld the first pass to fill the void and to heat the metal. then i come back and one the second weld do a slow side to side with a little bit of a circle to weld both sides together. and it works great
for the bottom after it was hot and from both sides being welded, i welded the bottom with one pass
i would suggest that the piece you cut out use it as a test piece and weld some 1/4 to it and then try to break it also if it is flat then it is easier than tring to weld on your side
i hate to weld upsidedown
here are some tips and info from lincon's webb site
General Usage Rules
As a rule of thumb, it is recommended to use a compact 115volt input (or 230 volt) MIG wirefeeder/welder indoors on clean new steel that is 24 to 12 gauge thick. 12 gauge is a little less than 1/8" thick. 24 gauge is less than 1/16" thick. The smallest wire(.025") will make it the easiest to weld the thinnest(24 gauge) material. The .030" diameter wire will weld a little faster deposition rate. If you need to weld 1/8" to ¼" thick material with MIG, you will need the higher capacity compact machine which will require 230 volt input. The higher amperage range of this machine can better handle your welding needs in a single pass and you may not have to waste time with second or third passes. The 230 volt machine could also run .035" diameter wire. To MIG weld material more than ¼" thick, you need a higher capacity truly industrial machine. If most of your welding will be performed indoors on clean material that is less than 1/8" thick, a MIG machine that operates on 115 volts is probably your best bet for economic reasons in that a 230 volt input machine will be more expensive.
The flux-cored process is only recommended on materials as thin as 20 gauge, a bit thicker than the 24 gauge we said for MIG. In general, this process is best for welding thicker materials with a single pass, especially if you need to weld outdoors such as to repair a tractor out in the field. A 115 volt flux-cored machine using an electrode such as .035" Innershield NR-211-MP will generally allow you to weld steel up to ¼"thick. Note that this is more than double the thickness maximum of 12 gauge with MIG on 115 volts. With the proper electrode on a proper machine, such as .045" Innershield NR-211MP, and a 230 volt input machine, you can weld steel up to 1/2" thick. Note that NR-211MP requires that the machine be setup for DC negative polarity.