Lou72240Z

I just rebuilding the carbs on my 72 z (car sat for 30 years), but now, I cant' get it to rev over 4000 RPM's. It won't free rev or while I am driving. It idles fine, but it is lacking the power it should have. I tried reseeting the float levels, made sure the lines and clear. When I try lifting the barrels, the front one almost stalls, the rear has no effect. When I place the flow meter over each carb, the fron one gives a good reading, but the back one makes the engine rev higher. This tells me that the rar carb is running lean, but I can't get it to increase the gas flow. Any advice?