I am a Pinot Noir fan, myself. Pinots are meant to be a liter wine than say a Cab, Syrah, or even a Merlot. A Pinot is a Burgundian grape, while a cab is a Bordeaux, if that really even matters.
This is strictly my own thoughts -
I would think a Pinot with a grape pack, other than a Pinot grape pack, which I doubt you can get, might end up tasting more like a Merlot.
I have added a cab grape pack to a Melbec and it turned out fine. But a Melbec is not nearly as delicate as a Pinot. The Melbec is heavy enough that the cab taste couldn't come through.
If it were me, I'd make it without the grape pack and maybe add some Tan Cor Grand Cru after clearing. It won't affect the tannic quality of the wine as much as it will add a little mouth feel, which I am guessing you are wanting the cab grape pack to provide.
If you do add the cab grape pack, it certainly won't hurt anything. And if you do, let us know how it turns out.