Which A-bodies do big blocks fit best in?

NONE. They're all a *****.
Take ya at least a day to remove the engine, but a small block comes right out. Headers are a nitemare, no matter what brand. You will be heating and pinging them to fit for days.

Take it from a guy who has raced a 440 Dart for years...Getcha a hot small block.
You'll be one very happy Camper.

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