I went with a photo tach and that works great. Mine is an expensive Monarch brand but the guys say there are cheaper ones on line with a bit of searching (I like my Monarch as I used them in dyno testing). All you do is put a piece of reflective tape on the dampner or anything else that rotates at crank speed (NOT belt driven!) and hook everything up according to direction. Problem solved and it'll fit anything you'll ever own in the future.

Dan