Regarding muskies.....they are in there.  I only have two musky experiences with muskies on the upper river.  The first time I saw one hanging out at the mouth of that tiny little creek that comes in just down from the footbridge.  He wouldn't hit a thing and eventually just casually swam away.  The second time I was walleye fishing and hooked into a big one, which eventually broke the line.
 
I fish the lower river a lot more, like around Sharpsville, but I only have one experience with a ski down there.  I caught one this fall around 35-40 maybe(didn't measure him).  There are more pike than skis in the lower river, not sure about the upper. 

The outflow of Pyme [ the headwaters of the Shenango ] is a well known hotspot for Muskies, especially so in the spring above the lowhead, but they are below the lowhead as well. My son caught and landed by himself his 1st Muskie there when he was 7 years old.

Muskies seem to be around Shenango upper and lower usually when your not ready . Mostly chasing Walleye is when they show up with me. I've lost Muskies both places throughout the years day and night fishing. Your right seems like the lower Shenango some years is packed with Pike.  Mikastorm is right seems like the super Walleye days on the upper Pymy flow have faded away. You would think with all that nice wood cover scattered along that river you would see some good numbers caught in the head waters. We took some nice Walleye out of there the last few years but no big numbers. One or two fish is about a average trip.
Lower river Musky being released by my son a few years ago (36")

I have fished from the **** down past the snowmobile bridge there is a decent hole down there.  I have never had big numbers but i dont ever remember having to measure a eye.  They all seem to be nice size.  In the summer when the lake water is tea warm i do really well at night from where the water comes out down to where the creek comes in

I remember years ago a guy catching a big ski right down past where the platform is today, this was even before it was even built. He was fishing for crappie with ultralite gear and he kept it.

For you guys that fish the river below the pymy dam what are your go to baits and tactics for eyes and muskie...no spots just how you fish them?

The usual stuff works jigs, stickbaits, and some good live minnows. Bigger is better...........sometimes.

No photo spot burn when you fish late at night ! LOL

I know I'm a fishing photo junkie................here's one more!

Did pretty well in the river below Pymy this past spring. Lots of walleye and some decent perch and crappies too.  Also landed a few musky and was bitten off by quite a few.....

those are some really nice stringers you got there congrats on the catch