Hello!
Never ever extend your highspeed needle ......a long highspeed needle will give problems to your carb setting ...vibrations you know!
On my airplanes were I can't use the regular high speed needle I have cut off the old needle at the carb, leaving only the fuelnipple and sweat soldered a thin tin plate over the hole ( I still use the fuel nipple though).
I then use a another needle placed in a more convinient place where the needle is easy to reach ( like at the rear of the engine cowl, between the cowl and the fuselage,10-15cm from the carb). I mount the new needle on a piece of steel plate or epoxyglass plate bolted right yo the fuselage.

Regards!
Jan K
Sweden