Like I said... the 109s' main advantage is pure speed. The best tactic would then be to extend straightaway until the speed advantage is substantial enough and try to rope the Spit.
Coincidentally, that is also how one would use a Dora to beat a Spixteen.
Or if you can hold out long enough, 109 has substantially more WEP than the corresponding Spit, translating into a major climb rate/energy advantage, in which case you would perform a climbing turn against the Spit, accumulating enough of an E advantage, and then cash in converting E into angles for the kill.