You only need a type rating for a 300 series king air in the US. If you are flying passengers in a twin turboprop it will be multi crew. Only the very smallest citation is certified for single pilot, insurance usually requires two in the front though. I also think it is the pilot not the plane who needs to be typed single pilot in the citation. All off the top of my head, seem to remember that but not sure.
As to weather or not you should do it. Completly up to you but what a waste of money, much cheaper to get away from the computer and go talk to possible employers. Clean king airs in the UK for 6 months and you never know you may end up flying one. I know that is below most unemployed pilots but it quite often works.