Just curious, have you gone in for a proper fitting at a store? Is it a hockey shop thats giving you the deal or is it used/private sale?
The only reason I ask is do not buy a pair of Graf skates that you haven't been properly fit for at a Graf authorized dealer. Each model is different, say from a 705 to 735.. the 735 and G35 are almost the same except for materials. I think the 705 and 735 are similar but the 735 was built for a wider forefoot than the 705s. 703s were for narrower feet.
The 700 series of Graf skates took in a lot of moisture and would get heavier towards the end of a game, from what I remember the G series improved on repelling moisture/drying faster. There are likely a few more improvements but I haven't used a Graf G series skate - correct me if I'm wrong, my advice is probably a little dated, I've only used a 700 series like 10 years ago, but I switched over to Bauers almost 3 years ago now.
I wore a 705 fine for 5 seasons, starting having trouble with 705s, then switched to 704s then 735s trying to find the proper fit. 704s killed my arches, the 735s was simply too wide at the forefront so my right foot shifted a lot. As I got older as my right foot is now almost a half size smaller than my left, so I tried Bauers and loved how light they were and didn't retain moisture, so haven't really looked back unfortunately. I would have liked to try a G5 but I don't think they're manufactured in junior sizes, I loved my 705s.