look for wood with no knots, tight grain (less than 1/8'' in width), also, look for grain that's as straight as possible from one end of the board to the other. knots and wide, wavy grain will cause the stock to bow even if you laminate. i go through dozens of boards looking for one that fits that description and if i cant find what i'm looking for i'll look at other types of wood although i try to stay between teak and genuine mahogany.
flooring material is probably too heavy and your gun will not float properly making it difficult to use and easy to loose if it sinks with the shaft out. i don't like mixing wood with different density because they contract and expend at a different rate and will eventually delaminate.
teak is expensive, mahogany is about half the price. if this is your first gun choose a wood that's cheap and practice till you are comfortable with the design and process , if you make one gun i suspect you will probably want to make more.
have fun.