I found my copy of the pool spreadsheet (had it in my home email, and spent 20 minutes looking in the wrong places).
There are 12 injectors remaining in the S2 L67 pool, but 4 of them were classified as 'leakers' or droolers the last time we tested them. Of the remaining 8, 5 of them fall into a 1.5% spread, but the closest injector to make a set of 6 would bump it to a 3% set. So sending in 6 or even 12 would be even better. The old injectors in the pool will probably be re-tested with yours (after rebuilding yours).
If you sent 12, it should be very easy to get a set sub-1%.