Strat,
I posed your question to some very astute, learned colleuges and here are their answers of which I concur;
connectegr
Maybe I will be smarter in my response over here in the AWS section. I have also done a little homework. Sorry for my learning curve. Provided that your weld falls with parameters of Chapter 3; base metal, filler metal, welding process, preheat, etc. So that all parameters are prequalified, then your WPS is prequalified and does not require physical testing. I believe in your case all the parameters are prequalified.
To give proper credit, I also asked the Chair of D1.1 and he clarified my poor understanding. http://www.FerrellEngineering.com Mr168
Yes, you can use a prequalified WPS with an 80 series filler under certain circumstances. You have to navigate around D1.1 Chapter 3 to find it, but the intent was to permit the use of fillers like an ER80s-Ni1 for A588 and A709 Gr.50W for weathering steel color match purposes. See Table 3.3 and paragraph 3.7.3 (in the 2000 Edition, reference may have changed in the newer edition).