The issue of 60 votes or 51 votes is a false choice. We actually need 111 votes: 60 for cloture (essential) and 51 for passage of the reconciled bill. The parliamentarian does not come into play until a conference bill emerges and budget points of order are raised against it. But before you get to this point there is a 60 vote threshhold to get a bill to conference.
Follow me to the flip side for a more detailed explanation.
Any 60 vote bill will be, necessarily weak. It has to be to provide cover to Blue Dogs to vote for cloture. Once you get cloture, the conference committee can do almost whatever they want to strengthen the bill so long as it has a greater than incidental effect on the budget. Public options, especially robust ones, have a major (salutary) effect on the budget and would be upheld by the parliamentarian (who can, in any case, be overruled by 51 votes, or alternatively, fired and replaced by a friendlier parliamentarian.
Conservative senators are not ignorant of this and may insist on a pre-conference agreement that the conference committee (selected by Harry Reid) will not substantially rewrite the bill to garner the 50 most liberal votes.
A final option, called the "nuclear option" would require the parliamentarian to disallow the filibuster in the first place. The Republicans, who have a track record of firing unaccomodating parliamentarians, considered this for judicial nominees a few years ago. Once you go down this path, Senate rule XXII (filibuster) would essentially be neutered forever. While many of us feel that this would create a better world, there are numerous conservative senators who would disagree as it would dilute their power.
I caution Kossacks not to be disspiried by a weak Senate bill. It is a part of the sausage-making process not suitable for children and those with weak stomachs or poor impulse control.