You could go with a compact unit like the
Shindy Daytona (at least sounds like a Triumph!)
If it was me, I'd prefer to install a round gauge in the OEM location.
There are a ton of options there!
Check out here for lots of possibilities
While you're at it, how about taking it one step further & upgrading the speedo to an electronic one?
You could accommodate the round 'analog-look' electronic speedo & sender from the 99-02 Sprint ST
I know the late electronic sender is form/fit replacement for the mechanical one (I checked that mechanical sender is same used on 97-01 S3 and I KNOW that is form & fit interchange with the 99-04 Sprint electronic sender)
That sender unit is plug n play swap
Or a lower cost DIY alternative for sender is
this solution
Here's a Sprint speedo that has been installed in a 97-01 Speed Triple cluster (same principle)
This on member
Lugan's bike -
http://www.triumphrat.net/sprint-for...otorcycle.html
It's a fairly simple wiring integration and relatively uncomplicated mechanical install to mount the speedo in the older gen shell.
Once you go electronic you can further improve the indicated speed accuracy by adding a speed healer as desired.