If they order an electrode with H4 or H8 designation, that gives them an upper limit on the electrode diffusible hydrogen. But they want the WELD tested, after welding in accordance with the proposed procedure? A4.3 and the applicable A5 spec dictate the base metal & welding procedure to be used for the test specimen, which may not be compatible with what the desired WPS has to say.
Can he fax you the spec that has this requirement? I'm wondering if simply ordering H-designated electrodes will do it for them.
Also try Houston Metallurgical. If they don't do it either, I don't know who in Texas will. And I don't see it on their list of services.
Hg