Nothing wrong with the 6505, it has its place. The biggest issue ive found with it is thats its really easy to make it sound bad through the wrong speaker. I wasn't a fan of it through a v30 which is odd because i love the v30. It did sound awesome through a greenback though. My recommendation to start with would be to get a creamback h 75 to replace that shitety stock sheffield in the combo. Cheaper than buying a set of bare knuckles.
If u decide to go the new amp route, get a laney ironheart or a h&k tubemeister. i own an irt and it rocks. i played a tubemeister through a engl greenback 112 in guitar center and that setup is amazing. Getting a tubemeister asap.
New pickups...well im a flaming periphery fan so my mind goes to juggernauts. I realize theyre not everyones bag, they require really consistent rhythm playing. Ive never played a set of pickups that good at everything i threw at it. On the other hand, if u wanna dial back the gain on the amp and push it with a high output pickup, ragnaroks or warpig and a cold sweat. If u just want something a bit more old school with a few modern tweaks, nailbomb and a cold sweat