I wove in some doubled yarns to try and firm up the sett spacing, then twined the warps. They are even-ish, not really dead on. I'm not sure if that's expected variation or not.
Then I started weaving. For a proper Overhogdal-style tapestry, the ground should be fairly even weave. (Looking at pictures of the tapestries, I think it's slightly weft biased, but you can still see warp threads.) I think my warps are too far apart, because mine is totally weft-faced. I wove a good 1.5"-2" or so last night, and now I'm wondering if I should just go with it, or if I should try and squosh the warps closer together and get an even weave. (Or even if warp spacing isn't the problem and I'm just beating too hard?)
In the meantime, I thought I should find some appropriate designs charted out. Lo and behold, the wonderful person at Southwark Stitches has several period Norse design elements from Oseberg and Overhogdal charted: