Well strats are interesting guitars to get involved in. I think it might be like building custom hotrods from parts. You could have a cherry '57 chevy, or you can get a junker and soup it up.
I was never a purist when it came to guitars, keeping them all original. But thats what fuels the collectible vintage guitar market. So many guys like me screwed around with their guitars customizing them in ome way or another, not always with the best of results. That reduced the supply of authentic, unadulterated 'mint' condition vintage guitars and made them rare even though there have been many thousands of strats made every year for decades.
One thing I did learn about strats, and vintage guitars in general, in fact all guitars is that there is little correllary between price and value. You can walk into any major guitar store and find a great playing and sounding instrument for a few hundred dollars, and also play instruments that are in the high thoiusands that have few redeeming qualities other than the asking price.
An old guitar does not guarantee a wonderful instrument, nor does a big price tag or a pretty face. I have heard of players who went through 50 or more Mexican strats and came away with one that was 'magical'. Strats have always been funny that way. Sometimes the neck, body and electronics come together in a way that just 'works', while another one off of the same assembly line is just dead sounding. You would think that in this modern age of CnC machines and consistent tolerences throughout the manufacturing process that all guitars would be created equal, but apparently this is still not the case. There will always be that undefinable 'Mojo''.
And then there is the players attempt to add extra oomph to those guitars that are 'mojo-challenged' by swapping pickups, refinishing, planing necks, re-fretting, routing, and other unspeakable horrors that make the vintage enthusuasts shudder.
Meanwhile-to address your reply- I do have a friend who put together a partscaster with a pre-routed body, ordered a specially configured pickguard and installed creme covered P-90s. Its a strange looking affair, a strat with p-90s. Sort of- 'Whats wrong with this picture?"
I like P-90s. I have two guitars equipped with them. Great for
slide. My 57 Les Paul Jr screams. Its a classic. My other P-90 equipped guitar has custom pickups that were special ordered to be underwound. Its a more refined guitar- beautiful cleans, not raucus like the Junior. Sedate.
I cant recall ever seeing a P90 in the bridge position of a strat along with two single coils, but hey- why not? It probably would be killer for slide.