Combining magic items with attunement

I am currently playing in a game where we have the option to create magic items per the new down time rules that were in the UA Downtime rules. I was wondering what people though about combining two uncommon magic items that have attunement into one but at a higher rarity the two I was looking at were the hat of disguise and the head band of intellect. I know I still need to get my Dms approval before I even try from it but I just wanted to see what people thought. I was thinking at a rare or very rare rarity with attunement of course.