Monoshock tanks vs 70's tank?

[jjwithers]

I need a R100S style tank for a '76 frame. I sized a '78 R100S tank and it fits my build perfectly (but it belongs to somebody else).
I have been offered a mono shock tank.
I know the underside of the tank is different then a late 70's tank and it might hold a bit less fuel... but is everything else the same on the exterior and fit?

[Bamboo812]

At some point BMW lowered the mounts on the tank and frame. A later tank on an early frame will sit higher...

[jjwithers]

OK. thanks!