There are many ST needle vales and look a likes out there, and be advised they are not all the same. All OEM ST needle valve assemblies are not the same. You need to know what length you need. The eBay seller shttrman ( aka Bob Brooks) has St type NVAs made for him by Enya and has them in three lengths depending on how wide your venturi is. I would order with this in mind. The Randy Smith NVA is a great part but uses a nylon seal to seal up the threads on the needle, and does not work like a collet lime the others do. If you tighten the nut too much it wears out the seal. If you need extra length on the needle, just solder on a length of brass tubing but don't get carried away. I have seen some guys add a spring/lnob assembly from a OS needle to an ST needle also.
Type at you later,
Dan McEntee