I have come up with a board design using Kicad. I have never designed a board before and this is just a prototype. Eventually I will break out the 328p from an arduino and just have that with the required components instead of using a full nano. There will be some other changed as well, I'll probably end up using the ACS724 sensor instead of the big ACS772. Also I will try to reclaim space. My routing probably isn't optimal, but it should be fine for a prototype.

I still need to figure out all the requirements for where I choose to get it made. And, I will be moving very shortly, so the time I can put into this is going to be minimal for the next few months.

Also I am working on getting timing. I think this can be achieved by comparing the rising edge of sensor inputs to each other. I just haven't sorted out the code. But it should be fine using the digital pins I am using for rpm, so it is just a matter of coding.