Speedometer mod questions

I want to run a 120 mph magnetic speedo on my 74 this will require a 2:1 Smith's drive.
Common with a 3/4" axle but I do not see one for the Commando axle. Am I just missing
it or is my only option to run up a different spacer than 06.7629? In fact, will this spacer
do?
Any help on this?

You could swap the gear sets out. When my drive housing got destroyed I bought a couple of cheap Smith housings off of EBay and put my old gears in. I also had a brand new drive that didn’t have the Smith logo on it, so it took the gears out of the new drive and put them in an old housing. This way they looked original.

Try a BSA B25/B44 2:1 speedo drive BG5330/31, they have the same axle size as the 1970 B44 VS. The 15:12 drive for the late B44 VS uses the same speedo drive as the Commando BG5330/171.

Smiths
Rear Wheel Speedo Drive
Genuine NOS
Ratio 2/1
11/16 = 17mm Bore
fits 1960-70 Triumph TR25W / 3TA / 5TA / T100
1968-70 TR6 / T120
1958-72 BSA A50/A65
1964-68 C15 / B25 / B44-SS
Triumph Part No. BG 5330/31
BSA Part No. 19-9212

OK thx