Regarding the valve cover gaskets:
Sometimes aftermarket covers don't fit the gaskets correctly. I've used a Dremel with a cut off wheel to widen the gap so that the gaskets fit correctly. Once they fit, use adhesive to glue the gasket to the valve cover, to ease installation.
You can trim the tabs off of the gaskets that have them, to fit your valve covers.
Regarding the clearance to the intake:
Just about the same story. Place them on the head and mark the areas that need clearance then use a Dremel to remove material until it fits. Use an old gasket, if available, while doing this so that the valve cover is sitting at the correct height, so that only the amount of materiel that needs to be removed is removed.
If the gasket was not in place when you took the picture. put it in place and see if the problem still exists. Note that a new gasket will compress when tightened so ensure that clearance is adequate for that.
A die grinder will probably work better for these modifications but most people in this hobby have a Dremel or similar tool and it works, just more slowly.
Lawrenceville, GA