You are concentrating on physically fitting the engine but don't forget the exhaust!
And steering shaft!
And removing most of the trans tunnel!
On 67 and newer swaps the steering shaft just barely clears the rear-most valve cover lower corner. That's after shortening the approx 2-1/4" tube that contains the lower bearing. A little grinding of the valve cover corner helps as does reducing the 1" diameter shaft. The column mounting holes can be elongated a little to shift everything outboard a little.
It could be a lot worse on the narrower A-body. It may require after market column and 2-3 u-joints street rod style.
I'm not trying to discourage you, just the opposite. I hope you move ahead with this.
