Well interestingly I too have recently purchased a vintage Lawrence L-250 from eBay. And just today I installed it in my Fender Mustang (partscaster) in the bridge position. It’s replacing a single coil SD Antiquity II Mustang pickup, which sounds fine but I wanted a little more drive from the bridge pickup.
I’ve only played the guitar a little after installing it but so far I like it a lot. It gives me that humbucker midrange and drive I was seeking - perfect for rock and blues. It’s not as twangy as the SD Antiquity but that’s to be expected and I still have a single coil Antiquity in the neck (which sounds great!). Both pickups balance well and the combination (both pickups on) sounds good. I might invest in another L-250 for the neck in the future but I’ll wait and play my current setup for a while before deciding.