Did you get anywhere with this? I’m not sure what permissions softaculous uses - I believe it varies based on the php the server is running in (mod_php vs suphp).
All worked out now Paul. Softaculous is working fine now in suPHP mode and Joomla is installing just fine.
Can’t remember what the details where, but it all got ironed out when we switched to suPHP, Softaculous did recognize the new suPHP chmod setting automatically. So all is good now.