[RICK LAKE]

llama man First off DON'T trim the bell housing, with it being aluminium.
If you are building a perfectly period correct cobra then look at theses ideas.
Move the motor mount on the frame. right to left, up or down. I can't answer for other cobras buy ERA builts the motor to sit about 1" off to the right for weight balance of the car with 1 person in it. Remove the motor and find the center of the car frame between the motor supports and see how far out it is. If it's a little, a 1/4" of movement should be all you need, if over an inch, cut off and reweld motor supports to the frame. Make sure you box them in when done. Slotted ones work the best and are easiest to move the motor around in. Have to remember that the mounts if rubber will settle with the weight on them over time, and twisting of the motor when running will also move things around a little.
Shim the motor with washers to change the height to clear the bell housing.
If it's just the backing plate( it should be steel) grind it down until you have 1/4" of clearance.
Is there a right and left motor mount? could it be flipped or wrong side on wrong side?
The other thing is to buy a good bellhousing for your self and your legs. Yes this has been done to death but either a Lakewood or Quick time would be the answer for protection and Quicktime has a tigher bell housing between the motor and trans. Things do break over time or abuse, having 10 little ugly,hairy toes and walking is great thing. Overbuild the car. If you don't like a red or gold bell housing paint it to match the motor color.
Has the transmission and mount been installed for the correct angle ? Hope one of these ideas help, if not you might want to take the car to a chassis shop and have them fix the frame and center the motor to 1/2" off right side. Rick L.