Re: 1970 115 johnson
1) Have your existing starter rebuilt at a local alternator & starter shop (probably easiest / fastest / cheapest)
2) eBay
3) any of the boat junkyards listed in the "Top Secret" thread, stickied at the top of this forum (Johnson & Evinrude Outboards)
4) the AOMCI website (aomci.org) classifieds section
5) kijiji / craigslist (probably in the form of a parts motor; easy enough to check if the starter spins)
Best,
Duncan