I haven't done research on your particular question, so I'll leave that to someone else. But just to address the underlying historiographical question, saying "historians have since praised" is pretty meaningless. A historian brings many sources together to produce an analysis of a historical moment or trend. Some make value judgements, but those will vary. Historians have differing analyses, and while they sometimes fit fairly neatly into original analyses, revisionist, post-revisionist and such, they just as often don't (and those labels themselves are subjective and used to paint a picture).

A historian can't tell you if it's a good thing that Ford pardoned Nixon. They can analyze what the political or social effects were. They make a counterfactual to argue whether it might not have been more advantageous for X group or Y motivation to pardon or not pardon. But those analyses and what they prioritize will vary.

Again, I hope a modern Americanist is able to address your question about the reasons and effects of Ford's pardon, but I just wanted to offer a word of warning. You won't find a consensus for what "historians praise" pretty much anywhere. Unless you mean just some historians.