If you can't wait longer than 24 hrs see if you can drive with the radiator cap loose. That will relieve the pressure and then wait for a week before turning the radiator cap all the way down. Stop and check to make sure you are not blowing out coolant. If you are running hot normally this may not work. Remember this is a "I don't have the money or want to spend the money type of fix".
When I bought my VX the previous owner had just replaced the radiator and said they cross referenced it a GM radiator and it was not that expensive. I won't be home for another six weeks so I can't check the numbers but maybe someone else on here might know what GM vehicle it fits
Mike