The're up for sale at Porterbrook and in a reasonably sorry state, but they wouldn't need much of an overhaul to be honest, since the control systems would remain the same. (Unlike chiltern's overhaul that means AAR equipment being fitted)
If we're short of EMU Stock short term perhaps the use of some Cargo-D or EWS Mk2/3 stock on the route, working in conjunction with Class 87, or 90 locomotives with TDM onto the DVTs for a 4 - 5 car rake could work quite nicely, especially for the Manchester Airport / Victoria - Liverpool services. The major problem would be that the running costs for such a rake would be a lot more expensive than that of an EMU. Unless the leasing costs for such stock could be kept rock bottom.
This does further come back to the idea of having a 'universal' Mk3 + DVT rake that can be pulled by any locomotive (including TDM and AAR Stock, add duplicate wiring) and an ETH generator in the DVT for use with Non-ETH Locomotives (Not needed for the 87/90).
Would be a lot easyer to throw together for the 87 or 90 though, already being TDM compatable and ETH, therefore easy to run with Mk3 or Mk2 stock with a DVT or DBSO on t'other end.