For an engine of that vintage, I would imagine the compression should be @ 150 p.s.i.
Most importantly, the variance between highest & lowest cylinder should not be more than 20%.
If you do a google search on " Suzuki/Samurai ", you might come up with some enthusiast/collector site.
Also, try this site & see if they have a manual for it.
www.books4cars.com
Here you go.
http://www.books4cars.com/result1~imageField.x~110~imageField.y~61~findmake~Suzuki~offset~50.htm