imac 2012 late change graphics card?

hello.... i'm lived in korea and i want to change iMac graphics card.

i'm using an iMac (i5 3470s, 8gb ram, gtx660m 512mb)--27inch iMac

so, my mother doesn't allow sale iMac...

1.change cpu i5 3470s to i7 3770

2.change ram 8gb ram to 32gb ram

3.change hdd 1tb hdd to ssd 1tb and 1tb apple hdd(my current hdd)

4.change graphics card gtx 660m to gtx980m..........

Can i change gtx660m to gtx980m?? it's possible??????

Hmm... I do well sicence and math but,,, i don't well English.... understand please......