When in doubt, draw a section detailing the weld and the applicable dimensions. The welding symbol only needs to consist of an arrow pointing to the joint, a reference line, and the tail listing the detail showing the welding requirements.
Al
From my understanding of your description, it does sound more like a 'V' groove weld than any other. However, if you are in any doubt or lack direct engineering input just go ahead with Al's suggestion and detail the joint.