i wouldn't worry to much about it. by the time you f@$k around with bits and pieces to get something that works, you have spent more than what a 4age conversion would cost.
my advice with a k series is to try to make the most of what you have got, or what is easily available. if it is a k series, keep it simple. otherwise do a conversion.
a 3k is a stroked k. a 4k is a stroked 3k. a 5k is a bored out 4k. a 7k is a stroked 5k.