W/W the Dragonfly's I've owned had a relatively large venturi and didn't like big props. You won't get Texaco-like performance with one IMO. Big props/slow speeds need lower compession and small venturis to run decently.

All the ones I have run were very sensitive to needle settings and a pain unless I ran them with a small (5x3) prop....then they'd run OK. A friend tamed his down by stuffing a short piece of med. fuel tubing down the venturi opening to reduce the diameter and increase the suction/fuel draw. Amazingly, it worked pretty well and really helped smooth out the run.

Good luck!