Bill,
Table 6.7 on page 234. See note 6, last sentence. Face A for both connected members shall be in the same plane. Not sure if you are performing angle beam UT.
Again my answer would be yes to the original post, scan on the "bottom side". according to the post the member is back gouged so essentially you now have a double groove weld so now your root is internal. Yes the technician should account for the groove angels. AWS dictates the angle to use for the exam, it is based on material thickness and not the bevel angle, but stipulates that where indications are noted in the fusion zones shall be further evaluated with different angles such as 45, 60 and 70 degree.
It's a simple exam for this connection as specified and need not be over thought. As long as the technician clearly specifies and marks the part as to his exam side and his X and Y orientation all will be fine.
Testing from the "bottom side" will produce the required level of quality and will eliminate additional variables as having to work the second leg due to the weld limiting the accessability of the transducer, since the posting stipulated that the bottom was "ground flush", and can be turne over. The thickness range specified requires the use of a 70 degree transducer set up to cover all of the weld and since it is ground you can run over the weld with the transducer allowing for full weld volume examination. The scan should be done from both the plus and minus sides of "X".
I know someone may start hollering about nearfield conditions and loosing anything at the surface while passing over the weld and you will have to use the second leg to check this area or check from the opposite side. This may have to be done if there are concerns noted with the exam. But AWS has specified procedure in section 6 that provides for the addequate exam of said connection, and there you will find the exam is addequate from one side using first leg passing over the weld. And from experiance I have picked up near surface discontinuities doing it in this manner. For AWS D1.1 this is acceptable.
good luck