If he's planning on having his receiver in the closet, I'm suggesting that he sets up TV1 for UHF, and makes the extension on the antenna so he may get better remote response. I do not recommend using the IR-UHF converter.
I'm not familiar with the 625. Can you set it up to use a UHF remote for TV1? I have a 722 and I don't think I can. So I'm speaking from my own experience. I do use the Radio extender to control my 211 from another room and it works.