225/6 to 273 v8 swap questions.

i am thinking of swapping out a 225 for a 273 on my 1965 signet.

I have a automatic, floor console car.

The question is aside from either sapping the k frame or putting in the conversion mounts what else will i need to do. Can i keep the transmission? Will it be as easy as unbolting the six and bolting up the 8?