I ordered the repro factory tach from Brothers last week and it showed up today. It took me a whole 30 minutes to install it and I didn't have to take the instrument cluster out. Pretty easy and straight forward to do. The wiring is about as simple as it can get and while it is a little tight working behind the dash it isn't that bad. I used a 1/4" ignition wrench and not much else. I'll post some pictures later. Yeah it's a little expensive and shipping is stupid too but it looks like it belongs there and besides if I was trying to save money I wouldn't be trying to fix this thing up in the first place
Just posting this to let people know it's easier to install than you think.