You have what is a common problem with the Kramerius records. Unfortunately, for some individuals who appear in the alphabetical list of casualties, nothing comes up for the actual casualty record. I don't know if this is because the OCR program being used misreads the name or if there is some other problem. In any case, I believe that the number 430 refers to the book number where the casualty report is recorded.
Soldiers who were from Vukovar appear to have been in k.u.k IR 70 if they were in the joint army or k.u. LIR 28 if they were in the landwehr. You might do a Kramerius search using the following terms:
Unfortunately, many casualty reports come up for this search but you may find your gggrandfather's report in one of them.
Alternatively, you might write to the Kriegs Archive in Vienna and ask them if they have the actual casualty report. I don't know what they would charge you do look it up.