As I understand, you planning to leave 250 million coins. So, swapping will happen in the proportion of 4: 1 ( URHOC : URS)?
nah probably in proportion of 1:1 , 500million is already in the burned address, another 250million is on another address, that leaves the 250 million URHOC holders.
Depends of course on how many of the people who joined giveaway are still here.