ProChem's Procion H Liquid Blue H-5RL 33% was a beautiful brilliant lapis blue, which they represented on their site by the gorgeous blue color on the left of the two chips below:

However, I gather from your message that it's the color that you want to duplicate, not the specific dye, and that you would prefer to use Procion Mx dyes. Procion MX dyes are similar in chemical structure to the Procion H dyes, but they react with the fiber you're dyeing at a much lower temperature. Where Procion H dyes require steam-setting, or application in a hot water dyebath, and Remazol dyes work best with hot tap water temperatures of at least 120° Fahrenheit, Procion MX dyes work very well at room temperature. Any temperature over 70°F will work well for Procion MX dyes, when you are using soda ash as the dye fixative, so there is no need for heat-setting at all.

I usually prefer to work with the pure single-hue unmixed Procion MX dyes, as listed on my page, "Which Procion MX colors are pure, and which mixtures?". The most brilliant medium blue among the unmixed Procion MX dyes is reactive blue 163, or Procion Blue MX-G, which ProChem calls Intense Blue, and other dye companies call Cerulean Blue. It is a lovely clear intense blue. (I'm including an image of this dye color from Dr. Steve Mihok's excellent pages on blue dyes for fly traps.) This color is a little more greenish than the color you are seeking. You can 'correct' the color to a truer blue by adding a few grains of red MX-5B (light red or mixing red or magenta, generically known as reactive red 2) or of red MX-8B (fuchsia, or reactive red 11). 

The hue of Procion Blue MX-R, which ProChem calls Basic Blue, and Dharma Trading Company calls Sky Blue, is close to the lapis blue you're seeking, but the color is definitely duller and darker, if you use enough dye powder to get an intense blue, so that's probably not what you're after. I would call it more of a navy blue. It's a nice blue, but not clear and bright like Cerulean Blue, and not as useful for mixing other bright colors, either.

You may prefer to buy a pre-mixed brilliant blue Procion MX blue dye. Consider ProChem's 404 Brightest Blue, which is a very popular mixture. Dharma sells a rather similar color in their mixture PR95 Procion Royal Blue. Premixed colors do not work quite as well to use as primaries for mixing other colors, but they are a great convenience whenever you find one that is exactly the color you're looking for.