Reading from the 1981 TDM (a great book at 25$ plus shipping)...
The european versions of the 116 motor show distributors 0 237 404 003 & 0 237 405 014 being set to 30 degrees at 3000 RPM WITHOUT vacuum (disconnect and plug BOTH lines). This presumably gives you TDC +/- 3 at idle or 15-19 at 1,500 RPM (both w/o vacuum).
Compare that with the US version with distributor 0 237 405 021, which is set to 5 BTDC at idle WITH vacuum, and should reach 10-14 at 1,500 RPM w/o vacuum.
So, you probably can get that extra 5 degrees. You may need to explore how the US distributer is different from the Euro. Not to mention the Cams and other control items on the engine.
I know the european motors have code 60/61 cams where as the US motors have code 62/63 or 68/69 cams. That implies different valve timing.