I went from O1 to EB1 and had to resubmit all evidence (and then some). There is definitely an opportunity for reuse, so assuming you didn't throw it all away, it should be easier to assemble your case than if you were starting anew. (I'm not a lawyer. Sample size N=1.)

See earlier comments. The standard for EB1A is much higher. That being said, the evidence used for an O1 often can support an EB1A.