Yes! The GPU and heatsink will not overlap each other. There are three common conflicts that I can think of:
-whether the GPU fits in the case without hitting the side
-whether the CPU cooler overlaps the RAM slots (though this can usually be solved by moving the RAM over, unless you want to use all the slots)
-whether the CPU cooler hits the wall of the case
The 300 shouldn't have problems with the 1st or 3rd, and the 2nd depends on the motherboard, but will only be a problem if you want 16gb of RAM.