There's absolutely nothing from a Type 3's FI that is interchangeable with your Bug's FI (except for the injector seals).
Your car does not need a new ECU. They never go bad, it is always something else. I have plenty of Bug FI bits if needed.
Well, I would argue the ECU issue. My '75 does not idle when cold, you have to drive the car for a good 30min before it will idle on it's own. We've checked the various sensors, etc according to Bentley, and came up with no issues. We pulled the ECU out of dad's '79 convertible, and my '75 runs like a top with nothing else changed. Dad's '79 won't idle with my '75 ECU.
...having said that, once the '75 makes it's way west, I'd love some help with it!
-Dave