would on pg 103 when Dimmesdale vouches for Hester be a type of irony?

I don't have the same page numbers you've been citing, but it is ironic that the man who vouches for hester is the reason she wears her letter of shame.

Another example of irony in Chapter Eight would be when the men are dicussing Pearl's future, and whether or not she should be aloowed to stay with her mother when the two walk up.

The most striking irony in the chapter is the fact that Chillingworth has become physician to the man he hopes to destroy.