Okay then, but some of the same principles apply so you might look at them from the library. There are ways to upsize patterns though.
Look at the stitch number differences between each size, it's usually something like 6 or 8 or 10 sts, depends on the gauge. Take your gauge times the finished measurement for the chest and that gives you the sts you need. See how many 'sizes' up that would be according to the size increments which you may have to round off a little. Then use that number to cast on with. This applies to sleeves and anywhere stitch numbers are mentioned, like after increases or decreases, the BOs for the underarm, etc. For the lengths, use actual measurements; if there's a sweater that fits him well, then measure it at the underarm to bottom, underarm to wrist, cross shoulders and from the underam to shoulder (straight up, not along the curve).
The other option would be to use top down raglan pattern generators where you put in your gauge and the finished measurement and it gives you a pattern. You can find them at Knitting Fool
and Knitting Fiend
. You can also use the 'percentage' method
which is similar and may be the one Knitting Fiend uses; the book Sweater Workshop by Jacqueline Fee also uses this method and is handy to have. These last are knit bottom up. Then there's the book Knitting from the Top by Barbara Walker which explains sweater construction as well as other things you can knit from the top down.