This is what you will need. http://www.nitrousoutlet.com/catalog...3&product=3786
Our manifold fitting is a dual accessory port and it swivels. With the style bottle valve you have this will be very useful in order for you to be able to place the fittings in the stoping position you need.
This will screw onto your bottle nut. Then the main feed line will screw onto the oposite end. The center of the fitting will have two 1/8 npt holes. In these holes you can put your gauge and pressure switch.
The blow down tube will hook to the NHRA fitting on the bottle valve. If your bottle has this fitting it will have a 8 an thread off the valve. If it does not you will need to purchase the NHRA valve. Can you post a picture of your bottle set up?