As long as the moisturizer is of acceptable quality, I don't think that "too much moisturizer" affects acne very much. [citation needed] To answer your question, I believe that either option would work equally well. I don't use SPF every day (in Canada we don't have to worry about sunburns for most of the year) but in the summer, I actually mixed my Olay sunscreen+moisturizer with my Acne.org moisturizer, so I didn't have to worry about multiple applications and multiple bottles. That worked well for the short time it was needed. I also do not see a problem with applying moisturizer, then applying sunscreen on top. I know that some people even completely replace their regular moisturizer with spf+moisturizer.

Now, to digress: when you say "normal sunscreen" I assume you mean a sunscreen that does not specifically also moisturize. Hopefully you don't mean just "any old sunscreen" because these can be quite bad for your face and have definitely caused problems for me in the past. Dan used to have a page on how to choose a sunscreen for the regimen, but I can no longer find it. I personally use a rather prevalent but highly recommended option: Olay Complete All Day Moisturizer with SPF 15. This was the one of Dan's preferences for sunscreen. I can't complain; I was pleasantly surprised that it didn't cause a reaction. It goes on a bit white, but it protected me sufficiently from sun damage, and I didn't notice a change in how moisturized I was. I will use it again this coming summer, though as a guy, I am not looking forward to strolling into the makeup section to get it.

Edit: I see that my digression was unnecessary: this is already the sunscreen you have in mind. I have used your exact combination before for a reasonable timeframe, and I have not had problems when I mixed the moisturizer with the spf+moisturizer, or when I put them on one after the other.