Wow! Congratulations. That's a choice set o'wheels.

What's the largest ring up front?
Do you think that triple crankset is worth keeping? Personally I'd ditch it first thing.
I ride with only a single up front and a wide range cassette in the back. and my bike climbs like a little dream.
I don't understand the desirability for having so many ultra-low gears in front on a 20" bike with a 53t big cog?
Seems to me that it just adds weight and unnecessary complexity to the machine.
Simplicity is bliss, especially on a fast bike.

That LX rear derailleur looks like it's a long cage, so maybe the current cassette already has some extra low gears on it?
You could lighten the bike by hundreds of grams by getting rid of extra rings, front derailleur, brifter, etc.