I absolutely agree with @cheapskate88 regarding the wheat protein, it is an incomplete source of protein and as such does not have all the essential amino acids that your body requires to construct muscle. Whey is more expensive and extremely proven in the bodybuilding community. Regarding the Soylent recipe, you do not need a multivitamin if you are going to be using GNC MegaMen this serves as your multivitamin source. You also probably do not need sulfur because due to improper reporting, the amino acids in protein powders provide all the sulfur that you are going to need. Thanks to @quidnyc for pointing that one out to me.
I would honestly say that after having thought through a lot of the issues that you are sure to face, please see my recipe and check out my blog to see the choices that I have made in my recipe and why I made them.
On a third point which is unrelated to soylent but highly related to your muscle gaining goals, I HIGHLY encourage you to read the book Starting Strength by Mark Rippetoe [Amazon]. Do not take any shortcuts, as a novice you have the absolute highest potential to advance quickly and Mark will explain how to get the most strength and muscle mass. Do not start training until you read this entire book, it will not take long.