I though this was a 289 it came in my 66 mustang coupe but I bought a aftermarket air conditioning kit and the crank pulley is 4 bolt not a 3 bolt that came on it I would like to know what this engine is and the year etc. also I need to change the harmonic balancer but don’t know what to get any help thank you so much

 

Block is 74 and the timing chain cover is 77, so it's a 302 block at the minimum.