Raymarine Smart Pilot S3G

[phantasy]

I have a Raymarine S3G autopilot on my 50 foot pwer boat.
I have been informed that the computer is faulty and advised to replace it for a Raymarine Evolution series computer and core pack cost about 1,200 usd without additional control head.

I have been told that I do not need to change the existing steering pump ?
I have been told it will integrate with the C120 chart plotter.

The main problem is that I cannot take any new wiring to the fly bridge where there is the existing ST 1002 Control head and C 120 chart plotter second screen.

My questions are.
Can anyone confirm that the existering steering pump etc will work with the evolution computer.?
Can I use the existing wiring to the control head on the flybridge if I use an adapter.?
Can someone kindly talk me through this.
Thanks in anticipation.
Stephen.