Personally I have never built a brass kit although the E9s are an interest of mine (specifically the UP engines and I have the latest Legacy version of the 949-951 A-A set).
I have always reckoned that I do not have the soldering skills for construction although I have done a minimal amount of resistance soldering. Plus there is the painting prep and actual painting, although from your previous posts you have all the skills, and more, needed for that!
Very much looking forward to seeing how you get on.
My only project of a similar kind is converting a Legacy SuperBass E7 B unit to run with the E9 set:
For whatever reason, Lionel has never produced any E8/9 B unit, or at least not one of scale dimensions. MTH has done a scale E8 in their Premier line, which is close enough for my purposes at least in terms of appearances. I have tracked one down and it will be a matter of my usual crude kitbashing to see if the shell will fit on the Lionel E7 chassis. The colors are generally a close match.
