If I can, I like to "play it safe" even if it's only by a marginal bit. If i had a metal table, I'd use the oxy/acetylene torch and fully bring it up to temp before welding and bring it back down. However, I'm limited to using a propane torch and the oven for as much of an even heating/cooling cycle that I can get. It's pretty chillly around here and I keep the garage opened up, so air cooling it would almost be like popping it in the refrigerator. I've read both schools of thought on how to treat cro-mo and for what instances and am more along with your school of thought with it. I use er70s-6 wire for all my metal work and don't have any real worries about it. I use a older millermatic 135 with the 4-click heat settings and find that "2" is giving the best result, which is a little on the hotter side than I wanted. (Miller says I can't retrofit my machine with an non-click incremental heat adjustment pot.) I am going to put a plate gusset to fill the top area down into the main tubes. I intend to drill out and install threaded lugs for heim joints at the ends for the spindle mounts and figure that as hard as I thrash things, a gusset might be needed.
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