Here's a picture of a 68 with the 250 emblem. It's not my car, just a picture I had. I'd encourage you to install that L6. I've been driving my two-owner, original everything 68 with the 230 L6 since 1988, I'd never consider changing the engine for a V8, there are tens of thousands of them. BTW, if your L6 has a smog system I'd be interested in seeing any pictures you may have. Thanks, Joe.