Here's the full ISO for 8.1: http://puias.princeton.edu/data/puias/8.1/x86_64/iso/
And then you can add the repos to update to 8.3: http://puias.princeton.edu/data/puias/8.3/
Or you can take the small ("boot") ISO and install 8.3 directy: http://puias.princeton.edu/data/puias/8.3/x86_64/os/images/
In fact, they are even building Springdale Linux 8 for i386, which RHEL and CentOS never did.
If you need more than three years on openSUSE Leap, then you need to upgrade to SUSE Linux Enterprise Server.
Here's the full ISO for 8.1: http://puias.princeton.edu/data/puias/8.1/x86_64/iso/
And then you can add the repos to update to 8.3: http://puias.princeton.edu/data/puias/8.3/
Or you can take the small ("boot") ISO and install 8.3 directy: http://puias.princeton.edu/data/puias/8.3/x86_64/os/images/
In fact, they are even building Springdale Linux 8 for i386, which RHEL and CentOS never did.
If you need more than three years on openSUSE Leap, then you need to upgrade to SUSE Linux Enterprise Server.