Mystery Sharks from Myanmar?

Check out the above - click for detail.

So, what Sharks are those?

I took the pic at Black Rock way back then in 1998. Back then there was no digital = this would be a so-called "professional scan" of the 35mm Kodachrome 64 slide - and yes those would be fucking hairs!

Anyway, there was a massive El Niño that was cooking the reefs in the Indian Ocean and beyond - but the hot water there was somehow causing a freezing cold upwelling in the Andaman Sea, and we were seeing plenty of deeper water Fishes like e.g. this rather rare Pterois mombasae we found at Richelieu Rock.

Check it out, it's an awesome Fish!

In brief, we were freezing our asses but having a blast.

Richelieu Rock was pumping with the usual Whale Sharks and a whole array of unusual critters among which mating Guitarfish, Kho Bon had dozens of Zebra Sharks and the Burma Banks, the usual assemblage of Tawnies and large territorial Silvertips;  and Black Rock was overrun with Manta Rays, to the point that we decided to turn off the engine of the dinghy and use the oars for fear of hitting one. 

We put down a few fish heads and had a few Grey Reefies come nosy about, only to be scared away by these two much larger Sharks. Both females and both likely shredded by mating, they came in hot and put up a short but awesome display of strength and assertiveness, only to quickly abscond with the bait.

There was quite some debate about the species.

Ron who was obviously way more experienced thought they may have been Graceful Sharks; I was more inclined towards them being unusually large Blacktips, and actually still think they are - and if so, they would most certainly be the largest such Sharks I've ever seen as they were clearly above 2 meters long. Or could they have been large Spinners - tho if so, where are the pinnae brevis?

Thoughts?

PS - Will confirms that they're most likely Blacktips. They look identical to Australian Blacktips (C. tilstoni) who are however strictly endemic to Australia - but thank you Julia! :)