Neither side vulnerable at rubber, South opens one spade. (He claims to subscribe to five card majors, three card minors, and strong 1NT but not "Flannery." He's also probably capable of "psyching.")
I (West) pass with (s)JT8xx (h) Kxx (d) Kxx (c) Kx. (All x's are 7 or lower.)
North bids three spades. South alerts "Bergen raise." That means that North has exactly four spades, but has less than six points non-vulnerable. He may have zero. (If he had six, he would have raised to two spades.) All pass. East does not have the 12 hcps he needs for a takeout double, nor the good six card suit he needs for an overcall.
South and North clearly aren't 5-4 in spades, and I believe that South is bidding "Bergen" style; that is treating AKQx as better than a weak five card suit (e.g. Qxxxx) because of his high sequence. This would also imply more than minimum values (15+ hcps). Put another way, I have no reason to believe that North doesn't have four spades and that South has five.
My inclination is to lead the J of spades, because South has fewer spades than his bidding implied (and was unlucky to run into a 5-0 split). Does such a lead make sense?