230Sprint6, I've never seen a hood tach for your car, minimal redline is 5100 I think. However, that does not mean a hood tach wouldn't work on your car. Your ignition is sending the signal, which is then converted internally. Don't know what reading you'd get?? Mighty interesting idea though!

Bob25, I don't know the answer to that either, though I do know the underside of the hood limits where you can actually mount it. There should be a triangular/rectangular cut-out(weight-reduction) point beginning 4-5 inches from the rear lip of the hood (in front of drivers area, as seen from the underside of the hood).
That area is the base spot for where the tach will bolt into. This allows the mount bolts to go through the hood, yet not go below the lower hood base and into the engine compartment, the bolt studs should be flush and not stick out (or IN, in this case). This allows the hood heat blanket to snuggly fit with no wierd bulges due to extended bolt studs poking in. Also allows for wiring harness to be run without creating bulges in blanket.
I looked at the template I have and it is generic for the GTO and Firebird. Bottom line is you may move it a little this way and that to get the bolts right, just make sure it is looking dead into your face from the drivers seat.
I suppose others with 400 hoods can tell you different, but thats what I have. Mine IS a Repro hood.