Actually the engine from the Espada was closely related to the 400 GT, Islero and Jarama engines.
Note that the Countach LP400 and LP400S actually used a slightly modified version of this same engine, with a new gearbox naturally, but still based on the Bizzarrini design from 1963.
Right up to the Countach QV, this engine design remained very close to the original, only from the Diablo on did it change rather dramatically, with original Lamborghini fuel injection.
Basically the same engine from the very first 350 GTV was modified and redesigned right up to now.