The technical manual contradicts itself in consecutive sentences.
"This allowed for a flat trunk floor and a bigger 80 liter tank could be fitted from November 1965 to the 230 and then to 250 and 280 SLs. The 80 liter can also be fitted to the flat trunk floor 230 SLs but the electric fuel pump has be relocated."
It says a bigger fuel tank "could bring fitted", but not that it was. Next sentence seems to mean "retrofitted" without using that specific term.
My car is Oct 1966, so I'm sticking to all 230SLs had 66 liter tanks.
Yes, I also pointed it out in my post - there are two somewhat contradicting pieces of information there, same thoughts as yours.
According to priceless manufacturing changes list from Technical Manual, we have:
Chassis 07205, October 64 - The spare wheel, which was previously at an angle in the trough, will be laid horizontally in the trunk, the trough is omittedChassis 14274, November 65 - Changes to frame floor, cross members and longitudinal members, to the 82Itr. tank and the stirrup suspension strut to be able to installSeems to me there were two waves of changes to the floor. After the first one, perhaps you would have to relocate the fuel pump, after the second one - not any more. After the second wave, it was all prepared for bigger tank introduction. Probably one of the marketing improvement messages.
And to mud water a bit...
As for fuel pump relocation:
the fuel pump cover changed at 042 07205, same as floor first wave of change
the clamp holding the fuel line to the floor was introduced at 042 07205, same as first floor wave of change