Looks good, I bet it's a hoot to ride!
My take on Suspension:
I've enjoyed riding my dirt bike with the off road set up,( just the wheels/brake changed) on the street with no adjustments. Fabulous, especially over any road bumps. And road riding it pays to be smooth on the brakes anyway. This was an off road bike, softer than your MX. Considering you are over the target weight for the KX, it might end up towards what I'm describing.
At the other end, I've had the suspension on another bike completely set up for Sumo.
Shortened slightly, stiffer springs and valving to suit. The best compliment I can pay is that I've never thought about the suspension when I'm racing, it just works. I haven't tried it on the street but suspect it would be firm, nice but less comfortable.
Personally, I'd ride it a bit and see how you like it, for what you describe, I wouldn't be surprised if it's great.
If you go for heavier springs, I'd recommend you get it revalved to suit the springs, and usage. If you can find someone that knows what they are doing, it could be worth it. (It would probably be worse for the "Dirt Touring" you mention - horses for courses.)
"Illegitimi non carborundum "
KTMs- '08 690Enduro (SM conversion) '06 450EXC '04 SX525 - Motard (Yee Ha)
'96 Suzuki Bandit1200S - ATS (All The Sh*t)
'08 YZ250F -MX raced so slowly, it's a sin
'73 Honda Z50 minitrail - Road legal, Vintage, Cool