Yes, Suntour are Sturmey, and No,the shifter is not spaced
correctly.
Use a Sturmey or compatible. They are not rare ( but the
cute red Torpedo driegang shifters are)
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
I have found that S-A 3 speed trigger shifters work fine with modern
Sachs hubs, so I'd think the opposite ought to be true. However, with
the "neutral" between 2nd and 3rd I would initially be very very
cautious.
--
That'll put marzipan in your pie plate, Bingo.