Guys, don't get too carried away here. 300 hours, or 400 or 600 it is a very small bit of experience. Sure, having acquired it in a Part 141 flight training program is good, but you have really only begun taking baby steps here. The FAA won't even let you fly cancelled checks in a C172 until you get 1200tt!
141 time is good, but most 141 programs are so structured that they don't allow for much actual IFR. I had friends who were CFII's at 141 University programs before they had a single hour of actual. I had to take control of an airplane away from a newly-rated CFII one night because he got spatial disorienation and started to lose control. Why was I able to fly it when he wasn't? Becasue I had scarfed up every scrap of non-141 flying time I could, and had actually been out flying IFR in the system, even sitting in the right seat on 135 flights, waiting for any Part 91 empty legs.
If you think you are ready for that regional job, and somehow you are offered one in this market- be sure of what you are doing. Some guys with 500tt or less have made it through some regional's training and progressed to the line, but many have also washed out, and I guarantee you it is a lot harder to get someone to take a chance on you with a training failure on your record, which, thanks to the PRIA, you must report to each potential employer for the next ten years!
Don't be so eager to get a regional job that you don't learn what you need to at this step of the way, including patience. Strive to master what you are doing now. Work as a team. Fly each flight with little to no deviation. FLy your ILS approaches within 1 dot at all times- and then ratchet up the speed, because you'll be doing 'em at 170+ kts on a regular basis, and anything more than a 1 dot deviation on the G/S or one half dot on the localizer will be a missed approach in the 121 world. . . start briefing each approach out loud. DO a before takeoff brief, including abort items, an emergency return plan, and decide who does what in the event of an emergency "I'll fly the airplane and handle ATC, you run the checklist items" etc. In other words, use this time to prepare for the future, instead of justy trying to get in the door.
Good Luck