Most 427 engines had cast iron heads...only rare L88 and L89 427's had aluminum heads.
There were five 427 engines available in '69...including the rare L88 and L89's. Much more common were the L36 427 390 hp...one 4-barrel. Next was the L68 400hp with three 2-barrel carbs. After that was the L71 435hp engine with 3-carbs, but as you said, it is a solid lifter engine.
If that car is original, it's definitely not an L71...it has 11:1 compression ratio. What's the redline on the tach? That's a clue...the L71 has a 6500 rpm redline. The 390 and 400hp engines have a lower redline.
Check the numbers on the block...the suffix for a 427/390 will be LL (manual trans) or LM (automatic trans). The suffix for a 427/400 will be LN (automatic) or LQ (manual). If the suffix starts with an "M", then it was originally equipped with transistorized ignition.
If the engine is original to the car, the serial number should match the car's VIN.
After this many years, anything could have been swapped out under the hood.