I prototyped a section of mast previously. The plan is to do a modified birdsmouth construction, from Jarrah and Tassie Oak (yes, these are my choice of timbers, both hard and dense), with comparatively thin walls, an integrated sail track, and slightly oval shape. Here's a piccie of my prototype, showing what I hope to achieve with the real thing:
A piece of rag tied to a rope that was laid in the channel prior to clamping served quite nicely to clear excess squeezage.
In any case, here's the glued halves, with some slugs chucked into the track to ensure it works nicely: