Thanks everyone for all the cautionary tips. I'm DELIGHTED to report that the engine runs! Weak spark was from the IGNITOR II ignition module air gap being too wide.
BUT frustrated to say that the timing is quite terrible. It won't run faster than about 400 rpm with full throttle, and dies as soon as I stop giving it gas. I timed it just as we agreed to in the earlier posts:
Ensured the EX sprocket was on the exhaust cam;
Used the middle hole on each cam sprocket;
Put #1 to TDC (Double-checked by actually making SURE that it was TDC, not just assuming it was by only looking at the flywheel timing mark);
Rotated each camshaft so that the sprocket timing marks were exactly next to each other and horizontal with the cover mounting surface;
Installed the timing chain and tightened, checking that the sprocket timing marks were still aligned afterwards;
Rotated to 10 degrees BTDC and installed distributor (10 degrees because it seems to be the modern suggestion instead of 5);
I played with the distributor timing by rotating it but it has no noticeable effect. The car ran REALLY well 2 months ago (before the teardown) with it at 5 BTDC, so I put it back to that, but same sputtering and dying results as it did at 10.
The owner of the car, before my father, raced it professionally. Perhaps he installed some altered engine components which require timing that is quite different from stock, which are preventing it from running smoothly. I still suspect the camshafts/sprockets are to blame. Perhaps it is not the middle holes on the sprockets? It's not the carbs either. They were recently rebuilt and were working fine before the teardown.
