tis 1 shud b ...... For example, you will say "If only he is rich, I would have married him immediately". You do not say "If only he was rich..." unless you are talking about a past proposal and you no longer know about that guy's financial situation. If you know that the guy is rich now, you will say "If only he was rich then...".
if oni he were rich ...
dun believe me? ... do a google ... :p