The post is older, but I would like to share my workaround.
First create a list of all SLAs in the admin area. The new list contains an value and description. The value is an id, later needed. The description is shown in dropdown field. The list contains one entry for every SLA.
We've six SLA types. So I set for value one to six.
Then edit the company form in admin area. In this form add a new field for the list created before.
So it's possible to assign a SLA to any company.
Next step we create filters. For every SLA Type i create one filter. The filteroption ist company/sla/level and filtervalue is the value i set in list.
In actions i assign the needed SLA and priority to tickets with the filtered value.
For example and understanding:
Listvalue 3 is set for 7/24 SLA
Filterrule is Organisation/sla/value is 3
Filteraction Ticket SLA to SLA 7/24
Hopy it helps anyone