305 project bike

Hello everybody, this is my first post here and ive been told this site has many wise kawasaki owners. A friend and i just picked up a '82 csr 305 that belonged to his late cousin. It has been sitting in a garage for 18 years and we just started tearing it down tonight. We have some basic ideas as to what it will look like but i wanted to ask a few questions to see if those ideas will work. Btw my buddy and i have been riding motorcycles since we were kids but this is our first project bike.
1. Will a kz650 tank fit our 305 frame?
2. We want to run a 650 rear wheel + brake setup. Will a 650 swingarm drop in? Im afraid of the rear sprocket not lining up with the transmission. What are our options? A friend of ours owns a BMW tuning shop and hes cool with making us whatever we need so fabricating stuff shouldnt be an issue.
3. We have a complete 2004 GSXR 1000 front end we want to throw on. What will we need to make that happen?
4. I know this is the chassis section but what are some performance upgrades we should consider?

Any help/info would be greatly appreciated.
P.S. - i know its alot of work and $ to throw into a 305 but remember the bike has Sentimental value and i guess you can say its a tribute bike.