Anybody who wants to Duplex or Articulate Marx PW steam is my kind of guy. Go for it.
The Marx e-unit or a new electronic one will both do; say, why not an ERR AC Commander while you're at it...?
Pictures, eventually, I hope.
(I built a "666" Pacific using 2 spliced/extended PW 666 boiler shells and a modern "K-Marx" 333 4-6-2 chassis; old outside; modern underneath.)