Absolutely. You're forgetting that the design of the Mk3s in comparison to the Voyagers is extremely versatile. No engines to think of, and no constraints of space to consider due to factoring in tilt profiling. There is more to work with on an Mk3. Less so a Voyager. An age difference of 20 years will hardly make a difference to that.
Take a comparison to a double 158 for example - which, until the pandemic, would only just about cope with loadings on the busiest of I7C routes (Inverness to Edinburgh in particular).
Compared to a double 158 and at a push a five car I7C HST, a five car voyager has;
- Fewer standard class seats (which defeats your first point - refurbishment cannot solve this without adding extra coaches)
- Less space for luggage due to body design (again, this cannot be solved without additional carriages)
- Greater fuel consumption
- Toilet emissions issues
- Requires guard/driver to both operate doors causing higher dwell times
- Less standing space
- Less bike storage space
- Higher leasing costs
- Greater purtrusion of vibration into the passenger saloon
- Not available until another three or four years
- Less legroom
In addition, they;
- Wouldn't be able to operate at 125mph
- Wouldn't be able to use tilt
- Would require six depots to sign them which is more hassle than what the timescale is worth at this point
- Would require platform lengthening to allow additional carriages to compensate for interior space inefficiencies
- Would require SDO
All this is before you consider what ScotRail/Transport Scotland want for I7C services, what passengers want, what they need, what the Scottish Government wants and most of all: the challenges involved to achieve this.
So remind me... what are the pros of running Voyagers on I7C runs again?