As many others have already stated and this is where a "machinist" comes into his own, don't buy, or pay someone else, to do what can be simply done yourself. There is much satisfaction to be gained from using your imagination, brain and tools to make something that works for you. "If" the narrower part of the T nut doesn't fit then it's not by much and a quick lick with a file would fix that. As far as the thickness goes then that could be fixed just as easily with a grinder, sander or file also. "If" Kroll really wants a machined finish to the bottom and doesn't have another toolpost then simply weld a suitably sized nut to a piece of flat bar and voila instant T nut.
And you have learned something along the way.
cheers Phil