I have to agree with NA265, especially since I got my start in corporate aviation in the St. Pete area.
At 300 hrs, you've definitely still got a ways to go, but the closer you are to the corporate scene the better, and, if you are a hard worker, it will get you noticed, which will get you an opportunity quicker (usually).
A lot of corporate captains (and airline pilots) got their foot in the door through working line service, especially at Jet Exec, on the North side of PIE. Don't know if they are still there or not, but I'd consider applying to work there if they are, and also at the other FBO's, of course.
True story- I knew a guy that worked line service at PIE when I had a single-engine airplane tied down there. When I came back four years later, looking for a 135 Jet SIC job, they introduced me to my new captain- the guy I remembered from Line Service. Even though I started flying before him, he got his opportunity earlier through working line service, and I ended up as his F/O!
Best of luck