I had a look into the pickups of those thin twins. I thin that if you are after the look, just go with a lipstick pickup, you can also check out GFS if you are on a budget. On the other hand, if sound is you concern, I think that the Kay "Sped bump" pickups are made more or less the same way. Those come up on evil bay from time to time, like this one:
http://www.ebay.com/itm/Kay-Truetone-Speedbump-Pickup-Late-1950s-Early-1960s-Tested-Works-Perfectly-/121210197040?pt=Guitar_Accessories&hash=item1c38b0d430
Another option that will probably sound more like the original is a low output P90 or a blade single coil pickup. Anyway, I'm just guessing here as I have only made a search and didn't come up with much more than a few pics of the thin twin pickups.