It can all be done. However...
You are dealing with big amperages and aluminum wire, and don't seem to know
what you are doing. That is a potentially bad combination.

I would have an electrician look at it. (Though someone here will probably
tell you exactly how to do it. Please get it right.)

Another issue (which you will probably ignore also) is that if the existing
cable is more than 8 years old, it is probably 3 conductors. You need 4
conductors to do it legally. I won't get into the issue of whether you need
4 conductors to do it safely; it is done to death here about every month.
There is no way to get around this; you have to replace the cable.