gen 2 conversion questions please help

[scottkusch]

I'm going to be converting my 00 cr250r to a 500...
Can I use my 250 cdi?
Will my frame hold up after tig welding?
Do I have to reinforce my head stay?
Would it be smart to replace my down tubes completely?
And can I get away with using the 250 rads:? (After I modify the outlet) cooling is my ?
And what kind of power loss am I looking at my fmf fatty off the 250?