The 1.3 intake will fit on but it will probably be very restrictive. The port sizes are a fair bit smaller and they can't be opened up fully because there is a waterway running close to the edge on one side. You might be able to source a 1.6 carb intake from outside the US, that would allow you to fit a downdraught 2bl carb, possibly a dual 38 or 40 Weber. Alternatively if you know a good ally welder you could get a 1.6 TBI manifold modded.