Dave, that ID site you link above is incorrect, it shows 58/9 identical, as Mike says yours is a 59 ....
here's a 58 - the difference in the 2 years is entirely the emblems .... the way to ID the year is the vin tag on the drivers door post
find the GM info booklet
here for 59, it'll have lots of ID info for model .... and wide front tires are very unlikely to work
Bill