Correct, the later ones with the quench pad hugging the exhaust valve more closely are better, but none of them are great. With a 225, the pistons need field glasses to see the deck, the most You can hope for is a really good swirl discharge from the intake port. Generating squish with zero-deck pistons, and a milled/filled chamber puts You into race squeeze territory, which is fine if that's where You're headed.
