
Again I would say to get a running 3HE and build them together. Even then you have to consider that you'll end up with a lighter 600 ... if it all goes ok. Cost of this will be about 1000
If you start to want bits from one or another bike that cost will rise quite quickly, a Thundercat front end 500, Thundercat engine, carbs, airbox, pipes, cdi, loom ... budget 500, back end with 17" wheel ... 300
Your original post said you wanted a cheap fun bike, I have to say the best thing you can do is break this sell a couple of bits and buy yourself a FZS600 Fazer for about 1200. This will be a money pit and probably end up as an abandoned project.