M-M,
Joe's (Baldwin) work involves replacing the 3r treads with 2 rail treads. Baldwin has done scores of Lionel engines. His work is exceptional and reasonable. I have a few of his conversions and am very satisfied. Plus he is a very decent person to work with.
On the curvature. With a fresh start in a barn running Big Boys you my want to reconsider the size of your curves. Minimum curvatures used by many 2 railers is about 60" radius or 0-120. IMO, that is where larger articulated engines start looking somewhat comfortable.
Many 2 railers use 72", a full 6' radius (0-144). Some of the best looking 0 scale RRs in large quarters going around the wall use 84" or 0-168. A 7' radius curve really helps keep the boiler overhang somewhat reasonable. Yes, I really do not like toy train overhang.
These curvature comments are very subjective. Best considered after viewing large engine operation on wide curves. With a barn format it would be shame IMO to run tight curves.
What about the possibilities of purchasing a 2 rail Sunset late Big Boy and adding the Lionel control? Has to cost less, no casting snap offs and never a worry about zink rot with "forever brass". Juss thinkin'.
