140 Johnson 4s for 20 cc?

[riffraff]

Hello all, what an awesome website. I just purchased a 1977 20 SF. I am going to glass in the transom and install a bracket and repower. I found a deal on a 140 Johnson 4 stroke but was originally going with a 200 Yamaha hpdi or efi. 2 questions: Is this enough power for this boat?
What bracket would you install with a swim platform? (the potter bracket is out of my price range) I know most of these topics have been addressed, but would like to see new opinions. Thanks in advance for your help.
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