6-cylinder gurus,... 292 or 250?

[lolife99]

I went a looked at a '69 Custom 10 tonight that had 292 emblems on the fenders. The engine looked to be all original. The engine did have an HEI Distributor installed,... but I know nothing about 6 bangers.
How do I tell if it's a 292 or a 250? (What year did they switch to the 250's) Which is better? Also it has no power steering. How hard is that to find, and will the 292 and 250 accessories interchange? (Specifically P/S)
All the experts please speak up. Thanks.