t8kc, congrats on the upgrade, the install should be fairly simple. There can always be some minor setbacks, but generally John has provided everything you might need.
Not having any crossover boards to pound out makes things so much easier too, although I am not sure if you will receive a new terminal board that will replace the current one or not. Either way, it is no big deal to pop the old one out. John likes to use hot melt glue to put the new terminal board in, I tend to like to use black silicone, it is a bit easier to deal with and a nice bead of it around the inner edge where the board goes will work fine. It just takes a bit longer to cure/setup, but doesn't become brittle over time like the hot melt can.
The new terminal board will have what looks to be like the older original heavy gauge clear skinned "monster cable" connected to it, and another connector at the other end which will then plug into your new can.
The new can will be already mounted on a new "baffle" board which will then be mounted right over the existing hole where your old driver went. This board is typically screwed in with the provided 4 wood screws. It really is just a matter of getting the new board/can assembly situated squarely on the cabinet top before screwing things down.
You might also get new grilles, as the driver can is a bit bigger around and also taller. At least my OW2 to 2.2000 was this way.
At any rate, take things slowly and pre-fit things first just to make sure you know how things will go together. The only real thing to be aware of is the orientation of the driver on the cabinet, and the instructions should show what way the driver should sit so that the tweeters are in the right position. Really seeing as there isn't the typical logos on the OW1 cabinet like the other bigger brothers, not much you can really get wrong here. Obviously if something doesn't look right, fit right etc., John will help you out.
Have fun and enjoy the process! And especially enjoy the music your Ohms will give you!