I don't know about the pointies, but the naked curvy tacho is dead-simple. It has a +ve a -ve and a signal from the spark plugs, which is one cycle per revolution. I had it set up with a signal generator (10v square wave) and that worked perfectly, so you could calibrate one that way.
The digital tacho you linked to has a 5V sensor which would make it more complex to install.
I bought one of these which works with the existing (curvy anyway) wiring:
http://www.demon-tweeks.co.uk/motorc...stroke-engines
It worked pretty well, but with the dual spark, I'm guessing the tacho has changed significantly, so all bets are off.