Main Stand Support Tube

So I have been busy stripping down my 1980 KZ750H so I can get the frame off to be sandblasted and get onto the rest of the parts myself (among other things). Today I took the swingarm off and was met with a pretty ugly sight. The tube that crosses underneath the swingarm pivot (has the main stand attachment and the back bottom left engine mount on it) looks like it has been beaten away at. It almost looks like the middle section was caved in to give enough clearance for the back of the oil pan - which would mean that something maybe bent.
How much clearance is there normally between this tube and the oil pan? Has anybody seen this sort of craziness before and could maybe enlighten me to how it could happen without the use of a hammer?

Never seen such a dented frame tube, who knows maybe the PO made some space for the engine remove and install. Leave it as it is and don´t think about it anymore.

That's the way the tubes were formed originally. The photo below is from my 750 (note the same deformations).

Thanks guys. I guess that's par for the course given some of the welding on these old frames ^^
I guess I can take the crank case out and get the frame blasted now