Iam getting my Mustang II IFS in on Friday. I odered one from TCI. I have a Miilermatic 175 Mig welder and have been doing a lot of welding to get practice. I feel pretty confidant in welding in the IFS myself. Iam using CO2 as my shelding gas cause I have it. Use CO2 on my Coke machine at my restuarant. My question is is bigger size wire better? Which size is the best to use? Iam putting this on a 1949 Chevy truck. Thanks!