Personally, I think the range limiting factor in a .270 on whitetailed deer will be your scope.
Most hunting scopes have 50MOA of internal adjustment, so you can only dope down 25MOA at best (without using an angled mount). A .270 with 130grn BT's will drop around 20MOA at 700MOA, and 30MOA by 900. Most people aren't great at holding over 10ft, but you COULD make it work.
At 700yrds, the .270win still has about 850ftlbs of energy, which is more than a .357mag at the muzzle. More than PLENTY to kill a deer without ANY arguement.
But truth be told, you did the right thing by passing on the shot. Without having fired your rifle at 260yrds and knowing the appropriate ACCURATE hold over, you shouldn't have taken the shot. The old "hold at the top of the shoulder" game works well enough, but it's not accurate enough in my book. For future reference, 130grn .270 trucking 3050 at the muzzle should drop about 4" at 250yrds with a "1.5" high at 100yrds zero"... Go stick a target out where the "Lucky Some Buck" was standing and test it out sometime before next season.