It is technically a sprint, which would mean shorter and faster strides, but 300m seems like a long race to run with short strides.

You do not take short strides when sprinting.
Your speed is a combination of the length of the stride & how many steps u can take within a given time.
The 300 is like the 400, it is a sprint.
You can not run at the same effort as the 100 or 200, but it is running a relaxed, very fast speed.
Some people r confused & say u should stride long sprints, but that is not what u should do.
Take off fast just like the 100 & 200, once u r at ur top speed at about 40 to 60 meters, then relax, & run to maintain that pace without trying to run faster.
To answer ur question u should run with as long a stride as possible, without over striding so u will run as fast as possible.