Pics would help, but based on the numbers and description it would appear you have a VERY early example of the 1989 SR600 model. Is yours 6 or 7 speed? I think the 7 speed stuff was introduced late in 1989, but who knows when your bike was built in relation to the frame construction date...

If the serial truly has 4 as the first digit, that's either an early production error or an indication that the dropouts were 128mm (halfway between 126 and 130). I've seen a number of 128mm frames but none with 4 as the first numeral. On the other hand, my experience with 1989 and later stuff is somewhat limited as I prefer the older 83-88 frame designs. If an SR600, likely it also has an aluminum fork (check with a magnet).