I haven't checked the schematic completely but the data transmission from the 8420 to the 43122 seems to be allright (as long as you choose the right modes for both parts).
On the 43122 there seems to be some mode select pins left floating - that can't be right. You should either tie them to ground or V+ (you might want to use a pull up/down resistor).
Are there anything specific you're not sure of?
Anyway I'm using the 43122 myself (as you know, ), but with a different approach. I'm feeding the 43122 with a good clock source that also drives a modified CD player. Like LC audio describes it in some of their material about LClock2. Well, at least that's how I will be doing it when I'm done.
Kasper