What do you mean by new style? Are you talking about the transfer bar safety? There isn't much that changed on them and if it was built before 96 it would not qualify for the barrel accessory program so H&R/Remington would not fit another barrel to it.
The one I had was purchased sometime around 1993. We sent it to H&R and they put a new thumbhole stock, new foreend and new barrel. Everything looks the same as the h&R I purchased this year. I think it cost my dad like $150