my recommendation is: if you've got a set of '57s, put them in the SG. Especially if one of them
is a '57 Classic Plus. An SG with '57 Classic pickups is one of the best guitars you'll ever find.
Get rid of the PCB and install good wiring harness, like plenty of us have already said. Once you've got
the '57s in the SG with a good traditional wiring harness, you'll have an instrument you might not sell.
The Schecter needs nothing, it sounds great. Leave it alone.
Put the 490T in the Strat and watch it get a whole different life. Or use the 490R...
Either one would smooth that Strat out a lot. A Gibson pickup adds a fine unique voice to a Fender guitar.
I said earlier that each of these instruments has its own voice, which might be useful for different songs or
performances. That's still true if you follow my recommendations, only more so.