A friend of mine has a 126 series merc and the oil gauges are mechanical, and the speedo drives from the transmission. the tacho is from the 15 terminal of the coil though. from what i know instruments light in yellow.... and the tacho is up to 6k rpm... i dont know if thats enough for you, but its not for me...
Personal thought is that i wouldnt go for it. to merc style for me...
Chris