Why do you want shorties..? Long Tubes are much better suited to the street RPM levels because they'll make more power for you in the engine RPM range that you'll spend 99% of your time driving at while on the street. Just be really careful on primary pipe and final exhaust pipe diameter. Have you looked at Headman headers..? They're about as high of quality header offered by a mega mass production outfit. I would go NO bigger than 1-1/2 inch on the primary pipe diameter or you'll knock a TON of low RPM punch out of it. Same is true for exhaust pipe diameter. The JBA shorty headers have a 1-5/8 primary pipe diameter. That belongs on something with at least another 60 cubic inches than yours, at least for a low RPM street car, anyway.
Look at Headman 88304.
Also, single exhausts will always out torque and out horsepower duals on a naturally aspirated engine, as long as the system is sized right. Just get a single inlet/dual outlet muffler for the dual look. You stand to make about 30 more HP and 40 ft lbs more torque out of a 289 with a single 2-1/4 pipe than with dual 2-1/4. Which, BTW, also translates into better gas mileage. Anytime an engine gains torque in the RPM that you cruise at, you will also gain mileage.
A single 2-1/4 will support close to 275 HP. Single 2-1/2 will support about 300 HP and a single 3 inch will support about 375 HP. Therefore, size the pipe accordingly. Less is almost always more. So when in doubt, choose the smaller pipe.
The less RPM you turn, the more the single will beat up on a dual, as far as the power numbers are concerned.