The February issue of Handloader magazine had an article on loading the 264 with newer powders.
The author posted a load for a 140gr Speer with 64.0 grains of RL-25 going 3,130. I'm not sure if he was shooting a 24 or 26 inch barrel.
Some of the other modern powders he tried are as follows:
All with 140 Speer,
MRP2 - 65.0 - 3,114
Magpro - 65.0 - 3,207
Retumbo - 65.0 - 3,171
Magnum - 69.0 - 3,240
Incidentily, he tried RL-25 with a 120 gr. Nosler Ballistic Tip... 66.0 grains at 3,440.
As far as 140 grain bullets for LR hunting there is a decent selection to try out and see what your barrel likes. Depending on which side of the Matchking for hunting argument you are on, Sierra's 142 hpbt is a heck of a bullet. Two other hunting bullets with relatively high BC's are the Barnes 140 XLC/TSX or Hornady's 140 SST.
I have been using 120 XLC's for the past few years and am very happy with them out to 500 yards. With a max load of RL-22 they really cook. I am anxious to see what the new 6.5mm Scirocco is going to be like. I wish Nosler would make a 6.5 Accubond too.
Neal