Want to put and aftermarket tach in a rallye dash

I did the LED strip lighting on my 67, also plan on doing that with my sons car. Of course he only turned 6 in September. Now the plan is to round up all all the pieces or at least most of it by the time he turns 11, then dive in on it. I figure between everything it needs done we should be done by the time he is 15 or so.