I'd get a 93 with the polished rims. The 92 has painted rims.
Good choices on the LT1 and 300HP with 6 speed.
Yes, there is a noticeable difference between an L98 & LT1 motor. The L98 is a torque monster and can rip tree trunks out but it kind of falls flat on its face in the higher RPM ranges where the LT1 starts to shine.
I would not buy an auto or a greenwood package but obviously that is your personal choice. Greenwood cars have less of a market when it comes to resale and personally I think most Vette Owners dislike them.
You should look for the normal mechanical things, try to get a car with a recent optispark and waterpump. Check for old weatherstrip, oil leaks, clutch, idle of motor, compression etc.
My suggestion is if this is your first Corvette purchase, that you bring someone along to help you and you also don't buy the first few you buy. Look at 5-10 cars minimum. I bought my first Corvette at 25 and now have had 5 over the last 10 years. Over time you become an expert on a specific generation and know what to look for. I still am learning about my C5 but luckily I have good friends that look out for me.
Good Luck