Help Identifying Torque Converter

I'm tearing down my 360 to address a spun bearing problem, and I thought I'd try to figure out what converter I have. (I bought the whole drivetrain used, so it's been a detective game.)

The only markings are these numbers on the crank hub: C300 2601.

It has 3/8" bolt holes. It measures 9 1/2" in diameter. It stalls to about 3200, flashes off the line to about 4000, and recovers to 5000 when I shift at 6000. Car runs 11.90's, weighs 3000 lbs.

It has this flexplate (It has a part number on it): B&M 10236 Chrysler SFI Flexplate 6 Bolt Crank, TF 727 w/ 360 CID While on the subject of the flexplate, this flexplate is for external balance. Is that what the cutout is for? Neither it, or the converter have any weights on them. The engine appears to have been balanced. It has KB 190's in it, and there are grinding (belt sander?) marks on the rods. The crank has different holes drilled in it than another crank I have, if that means anything. No Mallory has been added. It has the stock balancer with the offset weight cast in.

I bought it in 2009, and it had been running for a few years is the best guess the previous owner could make. He didn't build it. I just started using it a couple of years ago.