I'm sure that Reg still has some, I'll bet that he got a batch made, and for the relatively high price, I'd wonder if they all sold.
Someone else was making them from aluminium for a while, and it's not that hard to DIY, if you have some access to machine tools.
Get a longer bolt and cut it down. You'll have to machine it to get the groove in for the O ring, but that's not too difficult. Cut a slot for a screwdriver in the end, and you're done.
A longer adjustment screw is definitely a good idea.
However,. as Mk3Brent has stated, the TCCS should be able to adapt if you're running 550cc injectors, and an appropriate fuel pump.