First of all, there were no "I" casting date months. "I" looked too much like "1" so they skipped that digit. It's probably an "L" which would make it November 1964 not September 1964.
There's no reason the date span couldn't be that far apart but it's less likely. The block casting date would place it in a '65 model.
The 461 head castings were NOT typically 2.02 valves. In fact, when used on the 300hp engine they would have ben 1.94's. The 2.02 was unique to the L79 in 1965. The casting is the same, the 2.02 heads simply received different (and additional) machining. Of course ANY 1.94 valve 461 head can easily be made into a 2.02 valve head and there is no way to tell the difference if the machining is done properly.
Dale is correct, the EF codes out to 327/300hp with a Powerglide.
No idea on the value. It'd be worth a lot more in the car it came with than without. But if someone wants to build a non-numbers matching car with date correct parts it could be of some value to them. A lot depends on how complete it is and then finding the right buyer. A lot also depends on how modified it is and what the buyer is really after.
Short of all the details, I wouldn't expect it to be worth more than the average rebuild small block.
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Rich Cummings
Rich's 1965 Malibu SS Restoration Project Progress Page
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