Jameson,
With all due respect to PB, I would install the SR circuit before MQ. The accessory mounting plate of the MQ sort of limits access to the 9-pin sockets where some delicate pin jumping needs to take place. The absence of the MQ will make this easier, in my opinion. Also, the Teflon coated wire is fairly delicate and you will have more room to make the gradual bends required to keep it from breaking. I’m sure that PB has no problem doing this in any order, but amateurs like me need every break we can get.
Jamie