3How many syllables in the surname?
Depending on that, my probable vote is likely to be Christopher, but I'd recommend considering going with a C name if you can, because the spelling of the first name is ambiguous as to pronunciation. (That way, the naturally occurring variant Jay-Cee would still be correct as the child's initials. Of course, if you absolutely hate the thought of the child going by his initials, maybe not.)
If I was going with that pronunciation I'd just spell it Jace but otherwise I like the "C" name suggestion up-thread
Carter
Cole (my husband's name so I'm biased)
Cooper (this might be my fav actually)
Colton
Connor