Is there a combination of flathead pressure plate with a diaphram disc to mate a T5 to the flathead? I don't want to drill the flywheel to use a aftermarket pressure plate.
It's the pressure plate that determines the type of clutch, not the disc. A good clutch rebuilder can match a special diaphragm p-plate to many Long-drilled flywheels, or an off-shelf diaphragm p-plate to late '49-'53 Merc flywheels that are drilled for B&B p-plates, the same as regular diaphragms.
On our T5 set up we used the stock flywheel and pressure plate from our '49 engine. Astro van disc that matched the T5. All we had to do was open up the center area of the flywheel about a 1/4" to clear the center rivits on the disc. Works like a charm!
You might contact Gene Benson at Flat-O Products in Salem, Or. I think he stocks parts to accomplish what you want to do. He is a great guy. Ted H
h and h flatheads can help. i have used several motors from them setup for a 5 speed. -danny http://flatheads-forever.com/