With the the compression struts you can adjust the castor angle, i like quite a lot of castor, seems to be more responsive and self steers better when your doing skids but its all personal preferance.
If you would rather stick with a traditional arb setup i think a Mk1 capri one could work, they look to me almost identical to escort ones but the track of the capri is about 2" wider. If you want me to I'll run a tape measure over mine tommorow, just let me know what dimensions youd like.