I can't confirm any detail, but I worked on the re-opening of Wheal Jane by Carnon Consolidated in 1980.
At that time No2 Shaft went to 11 level, which would have been about 1100 feet. The shaft extended down to a sump below 11 level. That ties in well with your figure of 366m.
No2 Shaft was going to be deepened, but I left shortly before any work started.
Clemow's Shaft, the skip shaft, I think was already down to 15 level. Say that's about 1500 feet, which also ties in with your figure of 516m.
Can't remember if any deepening was planned for Clemow's shaft at that time.
Hope this is helpful.