pro street to pro touring style

[pronova]

i know when all said and done itllstill be prostreet more than pro touring but here goes my son has 33-16/15 rear tires on his 72 nova and skinnies up frront , he wants to get the big wheel look like 18or20s is there a tire thatll fill up his tubs that.house his steam rollers now, or will it look dumb? i stretched his wheel wells like 3.5 inches so it will need alot of rubber lol any and all help would be great if u have pics of the same transform or style change of what im trying to accomlish please post thank u