29x four coach EMUs would probably be okay for TPE's services through Huddersfield, though a little on the tight side (given the half hourly Liverpool - Newcastle plans, the idea of six trains an hour from Manchester to Leeds via Huddersfield...).
In comparison, how many four coach EMUs would you need for the 165/166 replacements in the Thames Valley (etc)?
All depends on the extra 140 carriages I suppose.