in terms of a good Latin gradus, Ainger and Wintle is the typical favourite, although F. Noel's and Quicherat's french versions are more complete. I also find Carey's Gradus useful.
In Latin, Maltby's is very useful but very hard to track down at a sensible price. Much cheaper and easier to come by is Jackon's Iambica, which although specialising in words tractable in iambic trims is useful for much poetic composition.
i don't know of the link, and, having tried it, it doesn't work for me,