You can easily convert any tap style (1st, 2nd or 3rd) (taper, plug or bottom) and make it into any of the other style needed. All you have to do is grind it. An angle grinder works wonders for this while it's on the wood lathe.
The 3rd tap, i.e. bottom tap can be used just the same however it is the most aggressive of all the styles and cuts the most materials and also the most likely to cause problems with the material as for cracking, shattering and the like.