I think Clint did a good job as Philo Beddoe, however, I can see Burt Reynolds doing the role--it's definitely in the same vein as Smoky and the Bandit
and Cannonball Run
. But, I wouldn't like it nearly as much. I just think Clint's a much more likeable person and that warmth comes across better than it does with Burt. But, maybe I'm biased since I'm an Eastwood fan, and not a Reynolds fan by any stretch of the imagination.
As for how it would be different... well, I'm sure we'd have a totally different cast since Locke wouldn't be Lynn, half the Black Widows (or more) are Eastwood regulars, and Geoffrey Lewis and Walter Barnes wouldn't be in it either.
And the soundtrack would be totally different too, since Eastwood had a hand in that as well.
Even with all the differences, I bet it would have still been a hit with Reynolds, since his other films of this style were such enormous hits. But I sure as hell wouldn't own it.