[Arran]

 I'm not so sure that a model 80 or 81 cabinet would even require grain filler, on the model 81 I have the veneer looks like maple, beech, or some other tight grained wood. In terms of sanding sealer I've heard that there is a universal water based type sold under the Varathane brand that is good for just about anything, and no it is not poly so your lacquer will stick to it, I wish I could find it in my area though.
  It may just be the lighting but on the model 80 cabinet that Kirk was working on the dark portions look a little too red, on my 81 they are a medium to dark walnut colour. I should add that my model 81's cabinet is a decent original, and other then the odd blemish which I will attempt to touch up at some point, it will stay that way, no point in adding more work to the pile where none is necessary.
Regards
Arran