1.3 8V = 63bhp, 1.6 8V = 80 bhp, 1.6 has much more torque and makes its power lower down too. They look very similar but the 1.6 is a bit taller and has a much stronger bottom end. The 1.3 on mine was pretty worn out so I went for the bigger motor. A 16V would have been nice but the 8V is a much simpler and cheaper swap, early 8Vs over here are carb and have the fuel pump on the head.
How much clearance have you got on the hood? You look to have a fair bit of lift so did you keep the 16V sump (oilpan?)?