The answer is "it depends" because I don't have enough information to give a good answer.
For Site A - You are getting rid of some number N of content pages and replacing that with a smaller number of content pages and redesigning the home page. I have a number of questions about that:
1. Are you totally deleting the content, or are you consolidating the content onto larger, more comprehensive content pages?
- Example: Today you have pages for [Great things about Red Shoes] [Tips on tying your Yellow Shoes] [The buying guide to Blue Shoes]. Are you replacing that with [The Comprehensive Guide to everything you need to know about wearing, tying and buying any color shoe]?
2. You mention Site B. Is Site B going to contain all of the content that was on Site A, or is it getting totally new content, but in the same subject area?