The Griffin, Dervish, and Valkyrie all fit the AFFS (and associated mercs) of 3025 . . . but the Quickdraw was almost exclusively a Kurita BattleMech. Sure, some have been salvaged as part of the AFFS, but this isn't a common design for mercs simply because most of the production goes directly to the DCMS.
Perhaps you might consider a Phoenix Hawk instead? Bit faster than the rest of your lance, but it is also produced in the FedSuns (by Achernar on New Avalon) and fits the 3025-era concept that said the AFFS consisted (primarily) of medium-weight designs.
If you really want a 5/8/x heavy, then also consider either an Ostroc or Ostsol. Both are out of production (so relatively uncommon), but can be found in all of the Great Houses and Periphery thanks to their wide-spread use during the Star League. One variant of the Ostroc found in TRO:3025 features jump jets, so you can still get your 5/8/5 lance that way.
MA