The problem with the 750 Sport is the o.e tyre sizes;
130/60 VR 16 front
160/60 VR 16 rear
Most tyre manufacturers (inc.Continental) offer a 130/70 16 front (Fireblade?) and a 150/80 16 rear.I dont know whether the two sizes are compatable tho.I dont know how wide the rims are,or whether those sizes would fit.I guess the tyre firms would know.Best get dialling and e-mailing then.
As for swapping the wheels for 17''ers,well thats down to the individual and what the bike is worth (not a lot,I guess).Depends if the bike is being restored "as origional" or done up to ride as a keeper.If its the latter then wheels of a later 900/750SS should go in without too much difficulty.Only you would need new discs as well 'cos the Sport used 280mm discs with no centres bolted to the wheel.New discs would probably mean the calipers would have to be remounted too,and so it goes on.I guess the easiest thing to do is bolt on the complete front end off a newer SS.Well thats the front sorted,now for the rear...............!
Best set fire to it mate!