Unless you plan on spending a ton of money, after you get the mag, the best way to go, would be to get the one that mounts in the Tach drive, which I "think" you called the speedo drive. The speedo drive on a 76 was on the front wheel. The tach drive is in the cam cover. I would stay away from the side mount one, just because they are prone to damage, in tight spaces. Nothing worse than having a mag, that will always get you home, with a busted cap from hitting something. The verticals are much more forgiving. Changing the cam cover, can get expensive. You have to replace the cover and cams, and much more time, because you have to shim the cams, and do a full inspection of the cam chest. The "Bolt In" mag, for you, would be the tach drive unit. But then, that is the easy way. If you want the hardest, just let me know. I can walk you through it all the way. After you spend around 1000 for the mag and mount, and a "good" cam cover and cams. I would guess around 1500, unless you find a used mag and mount. Good runners are on here all the time for around 500, most don't have a mount. Hope this helps.