Ok, so I'm pretty set on the Zeal Engineering daughterboard for the following reasons:
1. Dual VR conditioners. They're not as small or quite as good as the BrickEMS VR conditioner, but they'll get the job done.
2. 3 outputs. Instead of building 3 more transistor circuits to run the ignition from logic-level to power-level, you can use the 3 LED's + the 3 outputs from the MSExtra into the zeal board to give you 6 good transistor-controlled ignition outputs!
3. PWM idle control. I don't know if I'll need this or not, but it'd be nice to have.
4. Tach driver. Again, I don't think I'll need it, but it might be nice.
Though I still think that even with these extra output channels, I'll still need to build one more for the electric cooling fans. So I may just design/etch my own board, but we'll see about that (I may even try having a board made, found a new board-maker, and through-plated holes are SOOOOO much easier/better looking to solder). If I DO DIY my own, I'll do SMD components based on the same chip as the BrickEMS, as it's newer and better (and simpler). That, and I have yet to play with SMD components, and after my LED tail light project, I'm VERY tired of through-hole components!
I'm also looking for a cable that has all the pins populated. I haven't pulled mine apart yet, but as it's a relay board patch cable I HIGHLY doubt they're all populated.
I've also ditched the idea of using the relay board, There just aren't enough outputs on it for everything. Furthermore, half of the cable is useless as the entire top half of it is grounded on the relay board itself. Talk about useless. If I get *really* fancy, I might add another connector to the megasquirt box (DB9?) for the spark and fuel outputs.
I'm still trying to figure out what I want to do for the wiring harness. The majority of my problem is that I want to half-ass it. I want to both have a MS harness, but have a stock harness so that I can run the stock ECU while I'm still trying to get everything sorted. So, I'm trying to find a 2nd stock engine harness, ignitor connector, etc. Because who doesn't love spending twice as much?!
As far as actual progress, I did swap the jumpers on my stock board from "Opto" to "VR" triggers for the tach input and output, and I also added the 12v feed wire for the MSextra chip. So, I mean, that's cool and all.
EDIT: After looking over the zeal card again, it appears that the PWM and tach outputs are just more transistor circuits, so maybe I can make them work.