Supercharging a 440 Stroker

I am new to building a car from scratch but I am a mechanic by profession so I'm new but im not if that makes sense. I was thinking that I'd start engine and tranny since I need that installed to get my desired ride hight when Its time to mount the diff and it whould give me more time to see if I can stumble on a dana at the bone yards, or am I way off here too?

Also the junk yards close to me have a few blocks which is where I was gonna buy from and take to a machine shop to ensure it was good. Not sure what waranty they have on em' tho. Is this a bad idea for my plans? Their $1400 on 440source which is why I stopped looking but I'd rather pay that then waste money on something that won't work for what I'm building. Thats why I'm here to see what you guys recommend. Thx for all the replies...