If you want Blues Rock / Classic Rock sounds, you definitely want low output humbuckers ('59, PG, A2P & Seth) with 500k pots, as certain high output pickups might sound good driving a Marshall Stack (C5 for example) they sound too aggressive with just a bit of Overdrive for more subtle sounds.
I also mostly play Blues Rock / Classic Rock with my H/H Strat, although it can do Hard Rock & Classic Metal depending on what amp and or pedals I use...
I use a PG neck (By far the best neck pickup ever made) and a '59 bridge (the best bridge pickup I've tried, and I've tried a few: CC, C5, C8, PGb, A2P). The CC, C5 & C8 all sound great but are too high output and can't handle subtle stuff very well. The PGb had a great vintage vibe but I found it too bright in my Strat (But sounds great in a LP). The A2P had great mids and highs but lacked bass (Although sounds great in a LP too). So in the end I chose the '59 as a compromise as it has great bass and highs that cuts through and has a great vintage vibe about it, but it does have some slightly scooped mids. I've tried a A4 magnet in it to add some mids, but it loss some of its personality. I've also tried the Custom/'59 Hybrid, but to me it sounded just like a higher output '59. So unless Seymour Duncan comes up with a pickup with all characteristics of a '59 plus the buttery mids of the A2P, I'll stick with the regular '59.
I hope my experience with my Fat Strat will held you make a good decision on what pickups are right for you.
And if you do go with a JB/Jazz combo like you first indicated, I'd definitely go with 250k pots...