Re: want to put a seymour antiquity II in my strats bridge position
Vintage Strat pickups from the 50's and 60's tend to have the south poles of the pole pieces facing up. I'm pretty sure the bridge pickup in the EJ Strat is a south pole facing up pickup too. And it's alnico 5 like the Surfers.
The neck and middle pickups in the EJ set are alnico 3.
If you go with a regular Surfer I don't think you'll experience much of an increase in output between it and the regular EJ bridge pickup.
If you go with a Surfer Custom Bridge pickup, which are wound to over 9.5K DCR, then you would experience a little more output than the stock EJ bridge pickup.