Way, way too much. If you look at some of the posts here you will see dozens that point out that one should never add chalk or baking soda to water or mash unless one has demonstrated low mash pH with a reliable pH measurement. If there is a single reliable rule of thumb in brewing it is probably "Alkalinity - bad". In general, even occasionally with dark beers, mash pH is too high. Acid (the opposite of alkali) is required to bring pH down in most cases though with dark beer the pH is often acceptable without additional acid. For example, my dry stouts with 10% roast barley and 40 RA water come out at pH 5.55 or so with no chalk or bicarb addition. If you add the amounts of chalk you propose to you will wind up with a lifeless beer - malt flavors will be subdued because mash pH will be much too high. The beer will taste chalky - "like alka selzer" in the words of Gordon Strong.
WRT the spreadsheets - the Palmer apparently calculated SRM vs RA from a color model based on grist compositions. The slope is about 7 times what one gets if one looks at actual beer color vs the RA of the water it is brewed with (this doesn't matter much for light colored beers). Then, as if that isn't enough, calculates only half the actual alkalinity ascribable to a given chalk addition. IOW, for a 72 SRM stout if the Palmer spreadhseet says you "need" an RA of 300 the mean RA for actual stouts of that color is probably closer to 40 and if it says that you need 8 grams of chalk to obtain 300 RA you would actually need 4 (assuming that it is reasonable to talk about the RA of a mash which it really isn't). The EZ spreadsheet retains the RA-SRM correlation model (which it really shouldn't do because there is no data to base it on and the fit is very poor) but at least uses a more reasonable slope. The EZ spreadsheet also cautions against the use of chalk and explains the shortcoming of its calculation.
You don't say anything about the water to which you are adding all this alkali. Given that the proper amount is none for DI water with more alkaline water you are making it even worse. The only case where any alkali might be called for would be where the water contains a lot of permanent hardness (i.e. lots of calcium and magnesium paired with sulfate and chloride rather than bicarbonate) i.e. water that is very hard but not alkaline.