Red Motor Carby Spindle / Linkages

Hi All. I was unsure on where to post this as it could go in a couple of sections. A number of years ago I fitted twin Stommys to my grey motor. The manifold didn't come with linkages so I was able to purchase a set which joined the two carbys together via the spindles. The problem at the time was that the linkages had the larger thread for the red motor. I solved this by taking out the grey spindles and replacing them with some old red motor spindles I was able to find. The grey motor and red motor spindles are the same size in length only with a larger thread on both ends (the greys only have a thread on one end) and with the cut out for the throttle slightly larger.

Anyway I suspect that the carbys are sucking air and want to replace the throttle spindles. I have a mate who is going to turn up some bushes to fit but I want to source some read motor spindles. I can get some grey motor ones from American Auto's but can't find any red ones.

So I suppose the purpose of this is to see if anyone knows where we can purchase red motor spindles or offer any possible suggestions on what I should do in order to rectify the sucking of air. Is there a grey motor linkage set available? Your thoughts would be most appreciated.

Many Thanks Rod