Ryan Gosling would've slayed in that role, he'd have added some coy panache to it for sure, and as OP said a young Tom Cruise.
I've actually seen this movie probably 15 times (mostly in the background I have a lot of screens going on) and the Robert Redford one at least 10x. The '74 version is in fact better, specifically the acting and as a disclaimer I thought Leo did a great job.
Have to say the Golden car in the Lurhman version is one of my favorite cars from any movie. Some of the visuals and use of color are just fantastic.
I haven't seen Moulin Rouge, not my cup of tea, but I understand there's some finger prints of that style of saturated color usage and flair applied to the Leo version.
I absolutely love the typography and credit sequences that look like this;
My biggest complaint is actually the scene where they're driving into the city, pass a black family in a car who's blasting Jay-Z's "H to the Izzo" That to me was something that truly, if only for a moment, ruined my immersion. Lets just call it a WTF moment.
Bruce Dern's Tom Buchannon creates much more palpable tension, he's got a much more menacing gaze, I'd actually cite that as my biggest casting complaint when comparing the acting in the 2 flicks. The dude who they cast in the new one looks like some bizarro world Conan O'Brien on steroids. It's not exactly fair to hold the new guy to that standard though because Dern killed the role.
McGuire's on screen could've been improved, no doubt, the moments when he's overly nervous or overly quizzical or surprised are terrible and I'm pretty sure thats what OP's referencing. But I will say, doing the voice overs and narrating I thought he was at-least passable. I really like the final scene where he's wrapping it all up.
https://www.youtube.com/watch?v=oa5bRR8EHt8
Anyway my presence here will probably detract from the thread, apologies for that. Checking in I couldn't help myself seeing as these movies are in the top-5 of my most re-watched list.