Gidday there chap! Welcome to the wide and wonderfull world of the mighty KX500. Good choice of bike. You should get years of enjoyment out of it. If it runs sweet dont worry about pulling it down. These engines last for years and years without the internals ever seeing daylight. If it aint F**ked dont need fixin!
Try to get someone to plastic weld the tank up. No sense in spending $$ if your gonna replace it later on. Or look out for a black 04 tank on ebay. Although I'd say you'll be scratching to find one. You never know
. IMS makes a black tank for the 5 hundy that holds 3.6 gallons
www.imsproducts.com $225 Bills though. I managed to score a clear IMS of Ebay for $40. Average condition.
Carb is no worries good old clean out and set up according to the jetting chart found on this site will sort that.
Rad shrouds are obtainable through most shops (I think) I got mine at M/X South. UFO brand. Black is good.