Thanks!
I did misspeak - my 750 does have three separate cables(actually 4 I think but only need three for one side). But by weird coincidence an ex-PC repairman friend came by. After handing him a beer he looked at it. He thought that using the "daisy-chain" 6pins on the 650 for 2 of the 6 power connectors would be perfectly fine. With my fingers crossed we powered it up. Works fine and the infrared thermometer indicates no heat-up in the cables or connectors after about an hour.
So I am good.
By the way, for novices, it is not obvious that you need to connect the CPU cable, leaving the "tester" in place to wake up the power supplies. I put this tidbit here in the post for future searches.
I'm mining!
You did wrong you need six cables.
Three separate from one psu on the left side of the miner
Three separate from other psu on the right side of the miner.
Return them
Evga 750 p2 works has three separate cables
More efficient
And 2 of them are about the price