Does anyone know if this is possible?
Yes.
is there any way the A1200 can have its internal chip ram upgraded to say 16MB
No.
or would there be a problem/conflict with the way the custom chips work?
Well, several problems.
A) Custom chips can only address 2MB.
B) Some parts of the memory map must be reserver for custom chips, ROM etc. With all 16MB being chip memory there would be no way to access these registers or ROM.
So no, it won't happen, ever.
