Hello.
you can use any number for source/destination port number for ICMP. Since ICMP has no port numbers, SRX uses the ICMP sequence# as the port number, which can aid in troubleshooting.
for example:
show security match-policies protocol 1 source-ip 10.10.10.1 destination-ip 20.20.20.5 from-zone <zone> to-zone <zone> source-port 1111 destination-port 1111
Regards,
Sam