390 and 360 share the same block. Both stock have a 4.05 bore. 390 crank stroke is 3.78 and the 360 a shorter 3.50. Common 390 crank numbers are 2U and 3U and can been seen on the edge of a counterweight. Common 360 cranks are 2T and 2TA located in the same area. With mention of the C3 rods (C3AE-C I'll assume) I'll venture to say it's a 390. Also the C3 (63-64) rods are not original to the engine. 8J17 or 9J17 are the date code of 68/sept/17 or 69/sept/17 and the head date codes are between the center 2 valve springs. Remember to skip the letter "I" with month date codes as it was skipped and not used. So J is Sept. If date matching to the block they'd be fairly close to the blocks casting date. Within 2-3 weeks earlier or later normally. The C8AE-H heads are bread and butter heads used on many engines. It's the bolt pattern that's model specific. The vertical 8 pattern is common to trucks and larger pass cars. And the 14 bolt pattern common to S code (Mustang-Cougar-Fairlane) apps where the shock towers were close. Service heads are 16 bolt and universal for all exhaust manifold bolt patterns. Even though they have a C8AE-H casting number they can have a later casting date till 71 or thereabouts.