You will definitely need the 82 type block to handle this. I have one available for sale if you are interested, probably the last one on the planet including the transformer. Send me a private e-mail if you are interested and I will figure out what it's worth.
The 223 adapter allows you to hard-wire the speakerphone set into the phone. It was designed for use ONLY with 2830/2831 sets due to the lack of available spare pairs on 10/20 button sets. Technically, it can be used with a 2565HKM, but I don't have access to the documentation to make it happen.
Yes, you are on the right track about sending the line into the phone on the first pair, but you won't have any lights or hold functionality. I assume you already know that much based upon your previous posts.
