Just FYI, when I had my 427 S/O dynoed, (single 4bbl) it was done without an aircleaner. Just out of curiosity, we put on the Stellings & Helling unit and gave it another pull. No other changes were made. The engine lost 61 BHP.
I'd suggest the following:
1. Go with the K&N for general driving and maybe track use.
2. Unless you plan to put on 20,000 miles a year, do as I did and run no aircleaner. Just put it on for shows when the hood will be open. And no, you won't ruin the engine unless some knothead drops a bold down the carb. As much
oil as these engines use and as often as the
oil is changed, you'll have a hard time causing injury.
Just some thoughts from one who has already been there.
Al