No issue whatsoever. As long as they bloom together tree size will have no effect.

I believe apples are generally categorized by when they bloom: early, mid-season, and late. You want to have your apple trees bloom around the same time so that they can pollinate each other. This web site will let you check on whether or not specific varieties are good pollinators for each other. It also has a ton of information on apples in general:

http://www.orangepippintrees.com/pollinationchecker.aspx 

They're categorized when ripening, early, mid, late season and most will bloom and overlap each other.

Dorsett Golden, Tropic Sweet, and Anna are the only ones that will grow where I am (or at least recommended for any kind of success). I have the correct varieties. I was just worried that cross pollination required similar heights i.e. similar amounts of pollen. Blooming does overlap currently.