|>>|| No. 22875
I'm going to start this by saying that it's going to look like absolute arse unless you pay a lot of money. It looking blurry and shitty might all be part of the fun, but if you're interested in why your childhood memories are going to look like a smudgy mess on that TV then read on, I guess.
Converting old analogue signals to HD digital ones is just massively more difficult than you'd imagine. Upscaling a DVD to make it look "ok" on a 4K set requires a lot of post-processing, and the end result isn't ever great. All modern sets that have analogue inputs are tuned to this use case - they will process the fuck out of composite video in an attempt to make DVD/TV look passable.
Unfortunately, this means that the situation is significantly worse for retro games. The aforementioned post-processing tends to add hundreds of milliseconds of latency, which makes anything other than turn-based games pretty much unplayable. This can sometimes be fixed to some degree by enabling "game mode" on the TV, and that may be good enough if you're just messing around and don't care how things look. It doesn't address the issue of scan conversion and upscaling, i.e. how to take a ~320x240 analogue signal and turn it into a 3840x2160 digital signal, in 16ms or less. The Framemeister >>22842 mentioned does a good job of upscaling, and the OSSC is also great, but neither of these are the kind of thing you'd give as a gift.
To make matters worse, an un-modded N64 doesn't output anything better than s-video, and that TV doesn't seem to have anything other than composite. That'll be composite "240p", and most consumer sets make a right fucking mess of upscaling this. Early 3D games get a particularly hard time of this as the aliasing (jaggies on polygon edges) tend to be much more noticeable than in 2D art.
>I'm aware I'll need something like an A/V to HDMI converter
There are no cheap composite to HDMI converters that are worth buying; they are simply the same chip (very likely worse, in fact) that's in that Sony TV.
Getting an N64 to look anything other than absolute shite on a modern set is really pretty hard. I'll almost always go with the original hardware for nostalgia purposes, but for N64, I'll go for an emulator-loaded laptop every time (not least because of the framerate increases).