Further to Sunbird's comments, there are quite a few differences between the original Z-Spars mast base, and the current mast base being sold by
www.rigrite.com.
If given the choice, Dwyer seems to be the better choice. The Z-Spars mast has a reputation for being a bit weaker overall. Of course, if you originally have a Z-Spars, and you only need the mast extrusion, then get another, as you'll be able to move your hardware over to the new extrusion. This goes for Dwyer as well. But if you are starting 100% from scratch, and you will be buying the extrusion, mast head and base, hounds, spreader brackets and spreaders, and cleats, etc. then I'd get a Dwyer, and I'd probably work closely with Rudy at
www.drmarine.com and
www.dwyermast.com on getting the spar all set up properly.
I have replaced a stock Z-Spars mast base and deck mount hardware on a 192 in the past, so I know the differences, if anyone has questions.