Partial Sour Mash substitute for Acidulated Malt- Anyone experienced?

I am a new AHA member (been all-graining it for 4 years) and the first thing I found was this forum.  I found an interesting recipe for a saison that calls for 3% acidulated malt.  I have heard of doing a sour mash the night before to replace the A malt.  Has anyone done this?  How much grain would you use and at what temps?  Any advice would be greatly appreciated.

3% acidulated malt won’t give you sourness.  I expect it was in the recipe for pH adjustment. You could use 88% lactic acid instead. 100g acidulated malt equal about 2.8 ml 88% lactic acid.

But I don’t know about the conversion to a sour mash.

Kai