Aloha Skip,
In my opinion, I would top up the steering box and drive. The other alternative is to remove/loosen the front cover plate and that should allow most of what is in there to drain out. Then you can refill with the Penrite and most of the contents will be Penrite. I think the most important thing is to have some lubricant in the box. I have used 90W 140 gear oil and some grease smeared in the worm in the two TR3s I have owned without apparent damage.