the aftermarket 1.6 with roller tip is a good alt. to stock. plus with the aftermarket, you're assured every rocker is a true 1.6 ratio. you'll also prob switch to guide plates and hardened push rods. everything a plus to stengthen your valvetrain!
If the rockers and heads he's got now are the original 65 heads, then those don't fall into the "variable ratio" catagory that the 78-up heads with the stamped steel rockers do. The 65's had better rockers than the lateer heads. To upgrade to 1.7's he'll need to go to screw in studs & guide plates, his pushrods are already the hardened types if the heads are original 65's.