First off, 6.4 is quite old version of JUNOS and has been end-of-support for a while now. But from what I can see from your configs it looks like you are trying to perform interface-style NAT on the ingress interface before being sent to the egress interface. Normally I see interface-style-NAT applied to the egress interface. Try applying your service filter to ge-1/0/0 and reverse your match-directions. So NAT rule 1 should be match-direction output, and stateful firewall rules 1 and 2 should be output and input respectively. Also remove the address configuration on the sp interface as the this is not needed for interface-style NAT (keep family inet).
One more thing. Do you have an AS-PIC installed in your M20? You will need some sort of services PIC installed in order to perform NAT. Based on your configs you have a GE PIC in PIC slot 1/0/0. But your SP interface is also showing 1/0/0. Assuming you have some sort of services PIC, confirm the correct PIC slot as well and configure your SP interface accordingly.