I've got a brand new Bill Hincher Adapter Plate for a narrow block 4G63 to a 4L60E Automatic Transmission.
Was told that the plate shares the same Bellhousing Pattern as many pre LS equipped cars.
Sorry, but don't know if the T56 applies in this case.
I got the plate, transmission and accessories with a Wideblock DOHC 4G64 I recently picked up.
Don't intend to ever use it, so it's just sitting around right now, waiting for someone to buy it.