Hello Tom.
I would not expect to see you with anything other than a Simar!!.
I used to run Sachs Gems on our Nursery, the handbooks tell you to use straight 40 HD in the oil tank, if the oil grade used is too thin too much is delivered to the engine and they smoke badly.
You must also remove the small filler plug near the injector pump and fill that chamber up to the top with similar oil, it does not hold very much.
Good luck !
If it does not start well, you can still get the fuses ( zunders) on ebay.
Kind regards
Chris Fuller