The bellhousing bolt pattern between a 261 six and a TH 350 automatic are completely different, so an aftermarket adapter plate will have to be used. Most likely, the adapter will have some sort of mounting flange for a starter. You'll probably need to post some pictures of the engine/trans assembly before we can make an educated guess about which starter will fit. You're also going to need a modified flex plate instead of a flywheel, because stovebolt engines only ran Powerglide or Hydra-Matic transmissions- - - -never a TH 350. 235/261 engines do not have any provision to bolt a starter to the block. Early small block V8s had a starter with a 3-bolt nose cone that bolted into the bellhousing. Something like that would probably be the best choice to fit to a stovebolt/350 setup.
Jerry

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