In a word no, they are just about the limit - you can get biiger exhaust but you have to reduce the inlet then.. Different have builders have different schemas....
Wildcat heads will have the biggest valves if its bragging rights you want.
Depends how much money you have floating around!! 1.75inlets are as big as you can go without major surgery! with major surgery i have a set of modified rover heads with 1.9 inlets and 1.65 exhausts!