yamaha mq 1602 mixer pre to api style pre?????

Recently purchased an MQ1602 yamaha mixer for $40. Was interested if I would be able to use some leftover gar2520's and 2503 output trannies to create 8 channels of api 312 stylr pre's while being able to keep the EQ section intact and swap the 4558 for some ad8599's.

I believe I would still be able to use the 15 volt rails that are already existing. I would like to do individual outs on each channel.

Would I be able to use the existing circuit or would a full overhaul be in store for this to be done.

I am somewhat of an electronics newb still so be gentle and ease me in slow. have soldering and skills and have some more to the point circuits but am looking to use this as a great learning experience. I learn better by doing than by reading.

Even if there's enough room in the chassis to add in a DOA, you're going to need to upgrade your PSU. The DOAs will be sucking up a LOT more current at idle than what's there. If you were to do this, just take a look at the typical 312 preamp circuit and try to emulate it as closely as possible.

might be more worthwhile to 'cut in' an insert pre fader so you could patch in your 312 or whatever; rather than investing too much in shoehorning circuits into a desk that is likely needing maintenance.