Yeast for Merlot Syrah blend

[beekgeek]

Long time brewer first time wine maker. Getting 100 lbs of Merlot and Syrah grapes via a friend this weekend and trying to sort out yeast I should use. Looking at Wyeast 4267 (Summation red) or 4946 (Bold red). Any suggestions for this blend?

Aussie relatives would like to see a few gallons end up as a sparkling red. I’m thinking a high attenuation primary fermentation would be better there. Is the 4946 better suited to that?

Thanks