consult a tax lawyer knowledgeable in California LLC/S-Corp taxability. how Ca would treat the sale and how the IRS would treat it may be different. also, realize that what you want all capital gain is likely incompatible with the purchaser's desire to be able to write off any premium paid as fast as possible.
my understanding, nothing authoritative provided, is if you sell your interest as opposed to the underlying assets you get capital gain treatment for the difference between the sales price and your tax basis. the Purchase gets a basis in the LLC of the purchase price. The excess of the price paid over the FMV can not be allocated to the assets nor amortized as goodwill.
