The B-52 used different colors than all the other aircraft in SEA. At least for two of the three upper surface camo colors. And unfortunately, none of Tamiya’s colors straight from the bottle are a match to any of the Federal Standard colors in US military usage. All require some mixing to closely resemble the colors used.
THAT being said, for generic colors I would suggest (but not quite recommend)
for Dark Green 34079 try XF-61
for Medium Green 34102 try XF-58, XF-26, or XF-67
for Tan 30219 XF-52
for Light Gray 36622 XF-2 with a touch of XF-12 or XF-19
for SAC Bomber Green and SAC Bomber Tan on the B-52 I don’t know of what colors to suggest as a starting point really. For the SAC Tan, perhaps XF-49, but that is a bit too dark, and for SAC Green XF-22 or XF-65, but both need green added.