Lorenz had several ...just checked his web and for this engine size he has only that you mention.
I not home right now at work in Bodø so cant check what i used last year ..nut think most off the greve and other well know pipes will do the job just fine!
I think you will find the Os 140 as a nice easy engine to use just remember that the original bearings most likely will have to be change, both my Os engines got new bearings after a short time!
I use Skf stainless bearings and have great success with that... W 61904 2rs1 i think the serial number is ....