Hi!
You had an inverted (180 degrees) mounted engine and changed it to a slightly less 110-160 degrees tilting cylinder...The reson this works better is that oil is acumulating in the glow plug element when you have the engine mounted 180degrees (inverted) preventing good idle.
Inverted mounting of any glow engine should always be avoided if possible.

But...never put washers under the engine! It will be to little mounting surface and the engine crankase will easily get distorted that way. All engines should be mounted so that the beams holding the engine fits the mounting lugs on the engine with as much surface as possible.
Plastic mounts should always be filed smooth and square before bolting the engine down.

Regards!
Jan K
Sweden