more likely to have a carb fire from drastic timing issues creating backfire through carb..
I've seen many external gasoline leaks on engines at running temp that never made a flame..
however, if you're concerned, no harm in being prepared..
- if internal fire starts, continue cranking engine with no throttle input and should suck flames down and go out
- if fire can't be sucked down or starts/spreads externally, cover with damp towel to smother without mess and damage
- chemical extinguisher would be my last resort but may be necessary for large fire from external leak
good luck!