Combo unit recommendations

[KeithKris]

I'm not terribly experienced, so I'd love any insight people care to offer on a planned update to my new boat. It's a 1990 29 foot express cruiser that I will mostly use as a floating cottage. I am hoping to take some trips across Lake Michigan, but I probably won't travel much further than 100 miles or so in any single trip, and likely substantially less most of the time. I might drop a line here or there and do some trolling, but only when the mood strikes me. I'm not much of a fisherman. The boat seems well equipped - or at least it was when it was new. It currently has:

Garmin GPSmap 230
Apelco 560 fishfinder
JRC 3000 4kw radar
ST 5000+ autopilot

Everything seems to work reasonably well as far as I've been able to test. I'm just not a fan of the low detail maps and interface on the GPS. It seems like fishfinders have improved a lot as well in the last 20 years, so I'm thinking a GPS combo unit might be nice. I've budgeted about $1000 to put toward electronics. My short list includes the Simrad go7 and the Lowrance Elite 7 ti, both with Totalscan transducers. Any others I should consider? Here are my thoughts on the two units:

Simrad go 7 - A bit cheaper and maybe a better user interface, but only supports NMEA 2000 so I couldn't integrate it with my current autopilot or radar.

Lowrance Elite 7 ti - Doesn't look like the interface is as polished, but does have an NMEA 0183 port so I could integrate it.

What would you choose if you were me? Is the autopilot much more useful when fed waypoints from the chartplotter?

Also, I'm curious about how to best mount the transducer. My current one is through hull. It looks like the totalscan unit mounts to the transom. For a twin engine boat like mine is it best to mount between the engines or is there a better spot? Will this unit work well on Lake Michigan?