In fact, the redesign was made necessary because of restrictions on material use during manufacture.
The 905's redesigned Biogon shows that the original design - done in days before computers - was perfect.
It does so, by being in fact a bit less good (!) than the lens that has been on the SW(...) since 1954.
Compared to the old version, the performance drops a bit in the center. But it gains a bit in the corners. The new lens' 'best' is not quite (only a very, very small difference!) as good as the old lens' 'best'.
In the redesign, the lens has not been made faster. It was a f/4.5 lens in 1954. It still was a f/4.5 lens when it was on the 905.
The change from T to T* coating does not make a difference of detectable size.
So the most desirable SWC would in fact be the 903 SWC. The one before the 905.
More desirable than the older cameras, just because the older ones are older, and have had more opprotunity to wear.
But having said that, it is all more of academic interest than of real interest.