As others have stated, it really depends on what you plan on fishing the most. Like you, I pieced my boat together when I had the money and found good deals on CL. I bought my Bow mount Electric first, only because it was the first good deal I found. It worked out well for me as I was able to start bass fishing right away. If I was going to be fishing Big water I would have bought the kicker first.
You should be able to troll for salmon with your 75hp no problem. The big purchase I want now is the TR-1 gold. I have a Yamaha T-8 I may be willing to sell, PM me if interested.