Not quite complete, but very close. This is Mountain Klein #120
“Before” pic
The “Very Fast Red” / Yellow paint scheme is factory original to the bike. There are a handful of Mountain Klein‘s painted like this. Here is a pic from a period article.
I'm really late to the party on this one but can confirm that early Mountain Kleins had a 27.4 mm seat post and later ones a 27.2. The change was made somewhere around frame #600 - #800.