If that is on one cylinder only, you have a preignition event going on from some cross firing in the mag.
For the CHT at ground/run up power to have jumped that much, and have much lower EGT and run rough, that is a very likely cause.
It might be something else but without data it is hard to guess.
In any case DO NOT fly that thing. Do not even be tempted. Because if I am right, you will be very upset.
Find the root cause. Do not settle.
The two best investments you can make, by any financial test, an EMS and APS!