If you want to use an vintage SUN tachometer like used in CSX 2128 and a few others you can find these tachs on ebay USA. You have the choice between many 50th to 70th tachs. It will be a bit difficult to find a "Greenline" version and even more difficult to find the 8000 max revs version not the 8500 as I wrongly bought first :( . Then it gives the R.P.M. "Thousands" and "Hundreds" version. 2128 had the Hundreds version. What these old tachs all have in common: they used a transmitterbox with batteries :-(. 50 years old batteries don't work. You can find for insane money working transmitter boxes or electronic circuit boards which can be installed to get the transmitter box working. Well, not for me the electrical bungler. The option is to buy a repro Sun tach that looks okay except the dial. It's black/white. I dissembled both tachs (the old one was easy with a few screws, the Repro one was difficult. I hah to bead the chromed front frame from the body and had to bend the flange very carefully back after assembling the cutted and reshaped vintage scale. But it worked. May I glue on the black knob in front of the tach too.
To made the change from windshield frame (where the mirror is to located to) to single screen and vice versa easier I made a back plate for the escutcheon cover plate. If I use the single screen I have just to remove the escutcheon plate and bolt on the "mirror plate" which holds the Raydyot replica mirrors already :-)
Doors mounted. The cockpit and rear "frame" edges are not in line with the door eges but that was willful done. They are the same bad making as the original were done :)