There is actually a way to sync the flash faster than 1/250. It's a setting in some cameras have called FP (Focal Plane). There are drawbacks and it's only usefull in certain situtations however. That's why reflectors are so great for situtations like this, no need to worry about sync speeds.
...and shooting with anything under 50mm for portraits distorts faces way too much (makes them look
fat 
).