Vulnerability on f7

In the King's Gambit, White seeks to attack the vulnerable f7 square immediately. In the nineteenth century, this was business as usual among top chess players. As chess players learned to defend, these immediate assaults and the King's Gambit itself faded from popularity.

Below the top levels, however, the King's Gambit remains a potent weapon. I play it with some regularity every few years, then shift to other openings. Many of the instructive games that I use with youth chess players are King's Gambits.

Black to move

This position arises after the moves 1.e4 e5 2.f4 exf4 3.Nf3 g5 4.Bc4 Bg7 5.d4 d6 6.c3

White's intention with 6.c3 is obvious: bring the queen to b3 to construct a battery against f7. How should Black play?

This position occurred twice in the series of McDonnell -- De Labourdonnais matches in 1834. White won one and Black the other. McDonnell was White in both games. William Lewis had it in one recorded game. Tassilo von der Lasa had the position at least four times, three as White, before he was on the Black side in a game against Adolf Anderssen (one of the featured games in tomorrow's chess camp).

ChessBase Online contains 74 instances of this position. Black scores well with most moves. What is Black's best reply? Stockfish's top choice has been rare. Is the engine's second or third choice superior on positional grounds?