mini starters for a 1966 273 header install

You will need a 90 degree adapter that is the early version, like ones that came on a V8 Early A body. They look like the one on the right in the pic below. The bolt head in that pic was shortened by FABO member @65barracudaLA to clear his TTI exhaust pipe hooked to a stock manifold. A stock, thick bolt head may be fine with TTI headers, but check with them to see. If you use a 90 degree adapter like the one on the left in the pic, your oil filter will hit the frame rail. Notice how the one on the left is not a true 90 degrees like the one on the right?
90 degree adapters - SBM.jpg