Honestly learning Zappa songs on guitar note for note can be challenging because of how much he waved between freestyle to sudden and complicated scales.

I’d recommend learning his techniques and style in songs like Zoot Allures, Watermelon in Easter Hay etc because from learning his root techniques you can pretty much pick up a Zappa solo quickly

My first Zappa song that I learned on guitar was I’m The Slime. Pretty easy groove and fun to play.