First i agree with everything myv65 said. And secondly I also think it would be impractical to JUST do a press fit with lock-tite, some of the fluids you put in your system might corrode the lock-tite, so don't forget to look into that(you said you would already though)
also, i don' t know if you are doing a circular press fit or more of a rectangular one, but either way with the size you are talking it will be hard to make perfect. Even endmills and reamers don't cut perfect holes, so it doesn't matter all that much that you are doing it on a cnc, though you could get very close.
also, depending on the geometry/thickness of your block, if your fit is too tight you risk distorting the block (and possibly the flatness of the bottom) so don't forget to recheck this after you assemble the halves (if you end up doing it).