I did a very simple Ohm's law calculation to estimate the power draw in my console. I already knew the draw specified by my controller cage and I assumed the lights (which are all LEDs) were negligible. My audio system uses powered monitors and they are plugged into a different house outlet, as is my computer system - so they do not count in the calculation.
My SAMs (Reisner) have 30 Ohm coils ad only one of each pair can be fired at one time using the 12V supply, Hence, Ohm's law results in a requirement of 66 Amps for 165 SAMs. Although my final design had only 160, I had at one time planned for 165.
I have had my console in operation for almost five years with no power faults or any issues with the Astron 70A supply (other than its extreme mass!) It makes quiet a nice "bang" when I cancel loud registrations - but my house lights do not dim and I have never blown a circuit breaker!
There is another, more important issue you need to consider. Depending on the driver boards your are using to fire your SAMs, there is likely a limitation on the number of SAMs per board. You will have to wire the commons on your SAMs in such a way that they are isolated between these groups. Check with the supplier for your driver boards to see what, if any, restrictions there are.
It pays to do your design work and theory up front ...
By the way, you can see the blog I used to document my own console build at
http://www.nightbloomingjazzmen.com/Theater_Organ_Project.htmlperhaps something else there might be helpful to you. If my experiences can save someone else making similar mistakes, then I have been successful.
Les