Poppy,..What did you end up doing to the inside of the drums ??
I use natrual beeswax,..it goes on wet looking and dries completely clear. When I last did my SONOR kit I used 5 coats allowing a day in between. I do this every three years and right now I`m way over do. The dry wood has the best acoustic values, and the beeswax don`t fill in the pulp. It don`t build up and dissolves into the air eventually. It has no odor and no effect on the sheen.
Most drum companies use one of the poplar woods in between two hardwoods to get acoustic value that hardwood lacks. Beechwood is both hardwood and acoustic.
BTW raw linseed oil will not dry,...boiled linseed oil will !! Both will color the wood as well !!