Given equal crew skill, Number of guns isn't the sole thing to consider. Weight of metal thrown by a third rate (and with Africa you've chosen the smallest third rate in the RN - 64 guns rather than the more usual 74) will be more like 2.5 to 4 times that of a frigate - Africa via Constitution closer to 2.5, Bellerophon vs Hermione closer to 4 times weight.
Toughness of hull, scantlings, masts and rigging are greater in a third rate than a fifth or sixth rate (frigates being lesser to allow greater speed), even if Old Ironsides was notoriously tough. The frigate will be faster at most points of sailing and most sea states, the speed differential lessening as seas get rougher.
So a frigate should avoid a ship of the line. If it gets to a pounding match, the frigate is likely to lose, so it's best chance if battle is unavoidable is to stay at distance and attempt to dismast the battleship. That's a difficult proposition. I'd fall on the side of Africa many more times than Constitution, even though that's the closest frigate vs battleship fight there's going to be.