Never, ever let an INFP lead in a romantic cat and mouse game. If you think there is romantic possibility or more important you want there to be, make it hap'n cap'n! :P
My INFJ asked me out and made the first move after some stalling on both our parts. My other INFJ friend is very, very direct when it comes to dating and relationships.
But basically, go for it. His signs look good so you just need to tip the scales a little to a clear "yes" or "no".