Hi kosak.
In general, wood isn't the best mould material for vaccum bag/infusion due to it begin porous, so you can get air leaks through the mold, to avoid that you'd have do seal the wood pretty nicely, probably with a wood specific product or somethin (don't know much about wood), so you would have to work on sealing it and on the surface finish, it doesn't seem a good option for me.
In my opinion, it would be a lot of work which would not pay off, since there would be a big chance of failure.

Try a gel coat or a mold making specific product, followed by some fiberglass and resin, I know there are some nice mold making supplies to sell on the easycomposites website.