Gene is a well known builder and supplier to other frame builders. You can always get a range of different opinions, but he should take care of you. The only problem is if he has never built big frames, it tends to be guess work figuring out whether a frame will be flexible if one has never tried a particular dimension before.

The fact he is building in 4130 straight gage, does not mean it is not oversized. It may be just oversized straight gage. Some sort of a case can always be made for butted, but really, for those uses, and the size of the person involved, butted would be the least of my concerns. Height increases create direct increases in frame size, but 3rd power increases in the meat pushing the frame around. The minuscule weight difference is pretty meaningless. You are saving a piece of metal about the thickness of a few sheets of paper, about 3-4 inches wide and not even the full length of the tube. Buying a higher quality lock would be a more likely weight savings. In my experience one is not even saving money over 4130 butted tubes (at retail tube prices, in China, yeah, there would be savings), so normally the reason to go to the straight gage would because it is better in a given use, like less likely to show damage from rough handling, etc... Some people like the way it rides.