Clapton's SG was most likely a 1964 model.
Most likely the pickups were alnico 5 patent sticker humbuckers, not 50's pafs.
The magnets might have been 2 1/2" long alnico 5 magnets like most are today, or 2 3/8" short alnico 5 that Gibson used in the T-Tops.
The set would not have been calibrated for the neck and bridge positions and both pickups were likely wound more or less the same. Meaning that in terms of percieved volume the neck pickup would have seemed louder than the bridge pickup but only because when a pickup is mounted next to the bridge it produces a sound with less bass and more treble and less volume than a pickup mounted at the end of the neck..
Since his pickups were not calibrated you might consider using two 59B pickups. Two 59N pickups would be closer to what Clapton had but might sound too weak. Two 59B pickups would be slightly stronger than what Clapton had in his SG. I would probably just go for a set of calibrated 59 or Antiquity pickups.
The wonderful, smooth, singing tone Clapton got from his SG was because he is a GREAT guitarist with exquisite phrasing, touch and finger vibrato, and he played through the fabulous plexi Marshall amps of the 1960's turned all the way up. He did not use an overdrive pedal.
Unless you have his gear and can turn that Marshall up all the way, and you also have his technique, touch and knowledge of the blues, you're not going to get that tone.
The pickups I would look at are a stock neck and bridge set of Duncan 59's or Antiquitys.
I did alot of experimenting trying to duplicate Clapton's tone with Cream, and tried 2 3/8" roughcast A5 magnets and 2 1/2" roughcast A5 magnets.
I settled on roughcast 2 1/2" Alnico 2 magnets (stock in the Antiquitys) because ultimately, that sounded best to me and got me closest to the smooth, singing soloing tone Clapton got with Cream even though Alnico 2 is not what was in his pickups in that SG.
Clapton did leave the covers on, on that SG. but after I removed them to experiment with magnets I left them off of my Antiquitys.
I have 59's, Seth Lovers and Antiquitys in my five favorite PRS guitars, and stock RCA2 Antiquitys got me the best sound, followed by the 59's and then the Seth Lovers in the #3 position.
The 59's came with polished A5 and the Seth Lovers came with polished A2. Putting roughcast A2 in both sets resulted in a tone closer to the Antiquitys.
If you're on a budget, get a set of 59's and do some magnet swapping. Try roughcast A5 and A2 and see which you prefer.
If you can swing it, get a set of Antiquitys and call it done.
