The Webber DCOE is way too much carb for a stock engine. It's better to get your SU's rebuilt. Also consider getting your distributor rebuilt and have a Pertronix ignition installed in place of points. Try new plugs & wires, valve adjustment, timing adjustment for distributor, then the very last thing is to adjust the rebuild carbs. Assuming you have good compression those changes will make the car run like it's new.
Jim Lema