help with heater/ac air flow

I am working on a 1988 Z24 with A/C and I need some advice on what I can purchase to increase the air flow from my heater/ac. The air blows cold, but the squirrel cage just doesn't generate enough air flow to keep the inside comfortable on very hot/humid days. I have done the obvious stuff like buy a new blower motor and clean out the ducts, but that gave only very minor improvement. The flow on 95+ cavaliers is great and I want mine to work like those. Any suggestions? Is there a stonger blower motor available?