The OP needs to define “fit”.
If you have a one piece header it’s probably not a good header.
Best fitting headers:
Hooker 5303 (can’t buy them any more but it’s still the best all around production head header there is.
Hooker 5204 (can’t get these any more either) but this is the best header for 340-360 inch almost stock engines.
Anything else is just a pain in the ***. Do they go on easy? Nope. But when they are on they fit and they work.
Not a TTi fan.