Anyone on here ever used a Miller 211 mig for welding thick steel like 0.170" thick or 0.230" thick in all positions: flat, vertical, overhead?

I'm still kicking around the idea of buying a Miller 211 and using it for welding 6" x 9lb/ft or 6" x 12lb/ft H-beams to make a loft in my shop for storage.

Can't find a lightly used CST 280 for a good price, so I'm thinking maybe I just need to mig weld this instead.

Anyone got any pictures of out of position mig welding on stuff this thick?

Would you recommend using Flux-core wire for the extra penetration or would argon/co2 and bare wire be just fine?