I have a 69 Z/28 with a stock 302, Muncie M-21. I need to replace the clutch and discovered that I have a Lakewood bell housing and an 11 inch clutch, which of course is incorrect. If you are not concerned with originality, is it ok to continue with an 11 inch clutch and the Lakewood bell housing matched with the M-21, or for performance reasons, should I replace with correct bell housing, clutch, etc.?

If you are not concerned with originality stay with it. The original was 10.5 inch and a 403 bellhousing. You would also have to change flywheel and starter and possibly other items with the change.

Thanks for the advice...sounds like the way to go.