Well Malcom the best way to see this head brought back is to load on a ship to Nother Ontario Canada And I'll give it a good home ( Just kidding, but I wish I had that retro hardware )....
The wicks I discribed are exactly as you pictured, to get the right material take the old wick and stuffing out and bring it into a motor shop they will sell you something to make a wick from or a prefab wick that fits. The stuffing is probably just cotton waste and the new material you will purchase will look loke a roll of untwisted wool yarn.
And yes this machine can convert DC to AC power, both the commutator and the slip rings are interconnected to a common set of windings in the armature. In practice the DC winding is only used for starting but before mercury arc valves were used to rectify AC to DC large poly phase machines with this type of interconnected windings were used in industry, infact this worked so well some of these machines are still in service on my side of the pond 75 years after they were built. I would have set your machine up on a test rig to see exactly what it can do, but I suspect it should be able to charge your batteries as well as start your 6/1, perhaps it might even draw power from the batteries to supliment the Lister in a heavy surge ( Like I said I would need to test and play with it )....
As far as the varnish goes if you look inside the machine you will notice what looks like a semi gloss red oxide paint finish. This is not a primer but an electrical varnish used to supliment the original varnish durring an overhaul at some time in the last 25 or so years. Most air dry varnishes/electrical finnish are this colour when sprayed, brushed on or pour though varnishes are clear or amber. Baked on varnishes are also general clear or amber too.
This looks like its seen a lot of service by the carbon dust inside, it should be cleaned, but nothing in the pictures leads me to think this needs any real work provided the bushing are good, and the com and slip rigs are true.
Doug
You have something special here, I wish the indians had also cloned these along with the Listers....