Unless the existing moving coil meters are broken, I personally would not bother.
Digital panel meters are quite cheap to buy from dealers on ebay, but what you have to be aware of is that depending on the design of the meter, there may not be any isolation between the power supply to the meter and its measurement terminals.
This can lead to letting the magic smoke out of both the meter and your power supply unit.
If you really want to do this, check out the meters that are available and check their connections before buying, otherwise you could end up in a "why did I bother?" situation.
JimB