This used to be a very popular swap and I seem to recall a kit being available.
I built a 440 for a guy who was doing the same deal back in 1981 ish .........if there was a store bought kit available , I'd bet green dollars that there is one sitting on a shelf somewhere looking for you.
I seem to recall it being a very easy 10.80 deal , but he sold the car shortly after finishing it.
Actually , someone just had to have it would be closer to the truth.
But it was a pretty easy swap , with a minimum of cussing and only one ding required on a header tube.