I would recommend the 845HD belt for the 9.17 lower.
You might read through this post regarding my experience with the 842 and the 845 as well as the RPM vs the HD belts. Analysis is not scientific but the results speak for themselves.
You might be OK with the 842 in the HD variant. And you might be OK with the RPM in the 845 variant but not the 842RPM variant.
https://www.camaro6.com/forums/showthread.php?t=523261
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JRE Tuned (HPTuners) | 15% OD (9.17" crank pulley) | TVS2300 Maggie Heartbeat Supercharger - 14 psi | E-50 (DSX Flex Fuel kit) | JMS FuelMax Fuel Pump Booster | LPE Big Bore High Volume DI fuel pump | LPE High Flow DI fuel injectors | LT5 95mm TB | RotoFab CAI | AEM X-Series OBD2 wide band gauge | Elite Engineering E2-X catch can | Borla S-type NPP Cat-Back 3" exhaust | Forgeline GTD1 5-lug Satin Graphite | SunTek wrap | C-Quartz Finest Reserve ceramic coated