How much horsepower does a 5.3 liter 327 have?

There's no engine officially called a "5.3 liter 327". The "327" designation refers to a classic small-block Chevrolet engine with a displacement of 327 cubic inches (approximately 5.4 liters). The 5.3 liter engine is a later, different design from General Motors. They are not interchangeable terms.

Therefore, there's no horsepower figure for a non-existent "5.3 liter 327". The horsepower of a 327 cubic inch engine and a 5.3 liter engine will vary greatly depending on the year of manufacture, the specific model of the engine (different versions existed with different output), and any modifications made. You'd need to specify the exact engine to get a horsepower figure.