Paint Code Confusion ???

If you go to the TRACTOR PHOTOS section at the left side of your screen, and do a search for a 1934 Case "L", you will see my tractor that was painted with Case paint bought from a dealer.

The NAPA number you mentioned (NAPA # 99L-11464) is also listed here as the paint for the R and RC (unstyled models only), so it likely is much too light in color. OAN published the PPG-Ditzler paint "recipe" for several different colors including what is referred to as "LC Gray". Here is what Dave Erb of OAN says about LC Gray:

This is the most asked-for information. I get more phone calls for this paint than all the rest combined. It is no longer available from Case. No Ditzler color code exists for this color, but it can be mixed with the following information (This is the recipe used on my own model L, seen on the 1993 DuPont and 1996 Ryman Publications calendars):
FORD SPECIAL TRUCK FLEET GREY RECIPE #DAR 32974 toner # parts 486 5 400 73 490 293 495 313 499 1033
Mix 3 quarts of this Ford gray color (above) to one quart #9000 ready-mix acrylic black. You will get LC grey. (DAR refers to acrylic enamel)

I've taken great care to repeat this info correctly but have no L of my own so have not used this recipe - that's my CYA disclaimer. In short, it should be the correct color but I have not personally used it and I think that was a prerequisite in your post.