I think that's what I have decided to finally do to my swamp ash strat.
Shellac as a sealer, black aniline dye, then tung oil
I have just completed the dying stage and did a piece of test wood with the dye and tung oil. At first I was concerned that the tung oil wasn't drying, but we've had some wet weather over the last few weeks which likely contributed to the slow drying. Now that spring is finally here (a month late) in Alberta, the first test coat of tung oil has dried. I think I'm gonna give it a go on the body now.
One thing I probably wouldn't do if I were to do this project with hindsight is use the shellac as a sealer and to even out the absorption of the dye prior to dying. The shellac was too good a sealer, and really reduced the amount of dye that was absorbed into the wood. Consequently, the body is not as dark as I had hoped, but perhaps with the shellac on, it will darken up.
I will post my results.