It’s been over 25 years since I welded anything.No argument -- if you're building super heavy you'll need a big welder.
But my point is most garages don' t see big stuff like that. An 800 lb transformer bracket is typically 12 gauge channel, and for a big block engine cradle 1/8" wall 1.5" sq tube with 3/16" plates would be a heavy-duty build.
Both of those would be a cakewalk for a 120V Mig.
Teenage me replaced all the rotted unibody framerails on a vintage ford. Probably 1500 plug welds on 12 & 14 ga. steel. The car sat right, aligned and tracked straight and put up with all the abuse of a stupid teenager with a 1960’s v8 4-speed.
I did it all with a clapped out Canox 115v mig on argon co2 mix.