Tough choices! Really I think if you could fab something up will be best but it will take some guess work. The only issue I see with the plate idea is rough shift feeling if you don't have any bushings in there, but easy enough to fix. I think trying to alter the OEM shift arm will lead to failure. It looks like a cast aluminum piece and I think if you chop it and reweld it may not hold up. Completely guessing here though!

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Current garage:
'03 4.6is Proud X5 Peasant
'93 Jeep Cherokee (XJ)
'07 Jeep Liberty (KJ)
'88 Jeep Comanche (MJ)