The Prob I'd have when planning such an army is, that in my opinion a great amount of troops just will be mindless servitors and skitarii. Acording to the "Mechanicus" book from the HH-Range they use them for many tasks such as fighting aswell.
Then you have the "Knights", which could be a count as Sentinels.
and few High-level Command characters like Forge-Masters.
And of course no Forge is complete without one or two Reaver Titans and some Warhounds
