buick skylark resto

[druhi29]

I am a new owner of a 1970 buick skylark. It had a 455 pontiac engine in it when i bought it. I am replacing it now and i want to put a buick 455 in. My mechanic was suggesting that i go with a 383 stroker or a 502 chevy. I would like to stay buick. I found a 455 but am not sure if i need a short or long block and what is the major difference between the stage 1 and 2. If i change back to buick will i need to change the tranny as well? I also want to strip the car down and sand blast it. should i do this first or the engine work 1st?