there is a weird difference in the way different programs and different computers read how big a file is , if you have checked the file plays fully then i would not worry to much about what size it says it is ( different ways of calculating the file sizes )

and i like toast been using it for years , toast as well as other programs should tell you easily enough if you have enough space on the disc

apple macs should just be able to copy with no problems , but if it says there is not enough room on the disc then you have little chance as it knows the real disc and file sizes
my guess is the only real chance you have to keep the original size is if there is extra files you can leave out ? or i think you will have fun ?