327 chevy engine

Hi. I was browsing through the site at musclecarclub.com and I saw that the '69 camaros could come with either a 327 with 210 hp or a 327 with 275 hp. If I were looking at camaros in my area how would i know if the 327 was the more powerful 327 or the 210 hp 327?

Also, what would be the cheapest way to get a stock 327 from 210 hp to 400 hp, but keeping it N/A?

The 275 HP is a 4-bbl, the 210 is a 2-bbl. The "good" small blocks in '69 were the 302 (Z-28 ONLY) and the 350 (several versions, including up to 370 HP).
There's no "cheap" way to get 400 horsepower from a 327. Heads, cam, intake, exhaust, compression, etc. Not a problem to get the "little engine that could" up that high in power, but you will need all new everything... The later 327s were "large journal" crankshafts, the majority of which are cast nodular iron, rather than forged steel, unlike the small journal engines that were ALL forged steel. For a serious performance build, the cast crank becomes the weak link. Make sure which one you have before getting after it! Eagle does now supply a 3.25" stroke forging. Perhaps others, too. The factory steel crank is rare and sought after. It came in heavy duty triucks (327 "HI Torque") and Corvettes. There may be others, but I only know of these two applications.