What is your total budget with scope and air tank? I've tried scopes of varying cost and for me personally, to get something that does what I want (clear glass, thin reticle, repeatability) I'm starting out at about $300. You may likely want to get a 4500 PSI carbon fiber tank which will start around $500 to $600ish. If you stick with the 3000psi scuba tank, it will greatly limit the guns you can purchase as most reliable, "extremely accurate" guns require a fill pressure higher than that. For extreme accuracy in a rifle config, non bull pup, I'd look at FX, Kalibrgun, and BSA R-10. All of those are regulated (for extreme accuracy I would not look at unregulated guns) and will most likely not leave you wishing you had bought something different. The BSA and the FX Streamline are the least expensive but don't let that fool you, they are generally insanely accurate (although not a lot of data on the Streamline since they are new, but include the same time tested features) and the new version of the BSA has a newly designed regulator that is supposed to be better than the previous model, which I own and love. You could shoot flies off your dogs rear end with that thing, no joke.
http://www.pyramydair.com/s/m/BSA_R_10_MK2_PCP_Air_Rifle_Walnut_Stock/2200 The only one of those with and adjustable cheek piece is the Kalibrgun
http://www.wildwestairguns.com/air-guns-air-rifles/kalibrgun-rifle-.22-cal-wood-stock/ I've also had Kalibrgun and it was a very nice rifle, very accurate but I prefer the FX Royale Line up to it. The FX Royale line is time tested, reliable, super accurate.
http://www.airgunsofarizona.com/precharged-pcp/fx-royale-400-synthetic-air-rifle/ Lastly, if you're trying to keep cost down, I'd take a really hard look at the FX Streamline. It is a ton of gun for the money and if I had a hard $1000 budget for just the gun, it is probably the only gun I would be looking at. It will likely be just as accurate as all the guns here and also comes regulated, power adjuster, etc etc.
http://www.airgunsofarizona.com/precharged-pcp/fx-streamline-synthetic/