It sounds like you're looking for something like the Ares Spartan, referenced earlier. The discussion morphed a bit - Dreads aren't meant for combat inside buildings, they're meant for battlefields and urban combat (streets) with anti-drone combat, etc. The Spartan does good for reasonable power armor, however.

Pretty much what DocMortand said, the power armor that is using an Anthroform Drone chassis as the base is going to be as tall as a average troll at most, if piloted by anyone but a ork or troll. Most buildings in SR are large enough to accommodate an average troll, so there should be no problem fitting these suits into an average build. If you went with a modified JIM, the wearer would still be vulnerable to APDS rounds, and the point of power armor is to make your armored soldier all but immune to all small arms fire. For power armor that does not bend the rules, using Anthroform Drone chassis is the most viable route to take.