Richard,
The drains are there, at the rear against the bulkhead. Here are some pics of my 68 reg +4. I had the same trouble as you, water getting into the car in heavy rain. I found a tide mark in the heater air box and the drains that are above the bottom of the box. I lined the bottom with closed cell foam to raise the floor level.
Cheers
John
[Linked Image]
[Linked Image]