Cranberry stout

Hello. I have an Irish Stout recipe kit. I’m considering adding cranberry purée. Any feedback? Thanks

Cranberries are SOUR!!! Add a pound of lactose (unfermentable sugar) per 5 gallons to help take the edge off the acidity. Very important. You can add to the boil, or with the priming sugar later if bottling. For the cranberries themselves, wait until fermentation is about half done, then place the cranberries into a secondary fermenter and rack the fermenting beer on top of them. A good amount is probably 1 pound per gallon. Or maybe less since they are so strong, maybe 3/4 lb per gallon would be enough.

I agree that using lactose will take off the acidity, so that’s good advice.
Is this AG or extract? If AG I would consider mashing a little higher, around 154°-155° to keep some body since the cranberries will also thin the beer a bit.