I have a 94 OlyArms forged lower.  It's the one with the lion emblem stamped on it.  I'm looking for an upper for it and I know that not eveything fits it.  I've tried two different Bushmaster and both fit perfectly.  I've also tried RRA and Noveske and they don't fit right.  I heard Colts may fit but I can't say for certain.  The problems that I'm having are either the square male peg from upper that sits inside the lower and gets the takedown pin thru it is too thick and won't allow the upper the mate up to the lower or the other problem is that the upper will mate nicely with the lower, but the holes for the takedown pin do not line up, making it too tought to be able to work it by hand.  Any suggestions?  Am I limited to only BM's?

No, your not limited to bushmaster, its kinda trial and error. If bushmaster works, why not go with that? Nothing wrong with a Bushy upper.

you're right and that's the direction I'm going, but it would make it easier when lookinf for used uppers.