There is no dowload for JBossAS7.5. From 7.2 onwards it is counted internally to build EAP, but not for community releases. Here you need to use WildFly which is not what you want as the community bits are different and might contain other features as EAP.
You might talk to your client and let them test on the EAP version or regeister for an evaluation. Also you are able to use a so called self service where you can download the bits and have access to the Red Hat knowledgebase.