Error on Simulating 8-input NOR gate with Proteus 8
First, click on the option "show only parts with models" in the device selector. Then build your logic functions out of gates that do have models.

An 8 input NOR gate can be made from two 4 input OR gates going to a 2 input NOR gate. For a 4 input AND gate you just need a 4 input NAND gate followed by an inverter.  

However I suspect there might be a problem with your installation, because in mine (V8.3 SP2) the 4078 and 4082 both have models.