there is an old DOS program that was produced by the "American Welding Institute" named WELDSELECTOR that did a very nice job for narrowing down filler choices/selections.
Also - I am aware of an excellent program from Davignon Industries called FILLER2 that not only lets you pick dissimilar base metals from a data base of over 4,000 to find suitable filler, it allows you to select the process, filler diameter., complete and detailed joint design, position, etc - and then does a cost analysis with deposition rates, etc, etc.
Yes, a formal WPS should always be performed when required, but programs such as these can head you in the right direction pronto., especially when working with metals that you are not familiar with, including some of the proprietary metals.
Also - Once you are headed in the right direction you can use other references and resources to confirm.