There was a thread here on FAD written by a former funeral director in which she invited people to ask the tough questions about what happens to a body postmortem. She answered questions about burn victims as well.
It was a huge thread and I believe it's locked now for whatever reason, but I'm sure it's still there. Lots of good info there including burn victims. I believe it's called "Questions for Death Industry Professionals."
In Loving Memory of Timothy Houdek, October 22, 1969 - January 8, 2013
My awesome dad: Harry Houdek, September 8, 1933 - November 20, 2013
Words can't convey how much I miss you both. RIP with love.