I've done a lot of dicking with LEDs. Until I had my alternator blow the reg and fry my gauge cluster I actually had it setup so I could change it to any colour because I had RGB LEDs retrofitted...
If you just install the LED twist lock things into your dash two things will happen. One, main and annoying thing, is it'll be splochy. The LEDs don't output such a wide beam angle as the incandescents. They emit a fairly short beam angle as opposed to the incandescent. And the way the gauge cluster is setup it needs that wide angle to work right. So you'll end up with massive bright and dim spots.
The other issue is green. The reason the gauge cluster is green is because of a green film that's on the back of the gauges. This film also has a property to it where it can take light, and spread it out very evenly. So even if the light coming from the stock bulbs is a tad bright here, and a tad dim there, it evens it out.
I found that out because I sanded off all the green and put a red gel over the back of the gauges. Even with stock lighting I had awful hot spots.
So with the LEDs you'll have hot spots and slight green tinge.
The only way to correctly change the gauge cluster is to get LED strips and install them behind the gauge faces. Or you can make your strips like I did because I wanted 3 colours... Then make custom LED controllers, which is actually pretty easy. It takes 2 resistors, an LM317 circuit, and a capacitor.
I have a whole writeup on here how to do it all. Somewhere.... It was from like 2008 so it might be hard to find.
You could also experiment with slightly brighter bulbs and bulb condoms. But I doubt you'll have a huge amount of success that way. The bulbs have blue condoms on them anyway to raise the colour temperature.