8 gal is too small. Get the keg, borrow some tools or find someone who has tools and is willing to help. Mention "beer" and you'llbe suprised how much help you can get. Especially when "beer" is accompanied by "I'll give you some".
rent/borrow an angle grinder
rent/borrow a drill
buy a few cutting disks and a whole saw bit and some cutting oil
I actually know of a blacksmith that cut the top of mine for me for $20, another $10 for the bit and oil and the cost of a weldless valve you'll be a lot happier then you would be with a 8 gallon $150 kettle
You may also want to invest in a thermmosight because TRUST ME sticking your head into a kettle of boiling wort tryng to guess at how much is in there ISNT fun. http://northernbrewer.com/weldless.html