I’ve had real good luck with Transmission Specialties behind my small block powerglide combos. It’s a spragless 8 inch turbo spline. I’ve never given them dyno numbers because I don’t dyno my stuff but when I told them I wanted 5800 stall on my last freshen it came back at 5760. I consider that pretty close. I will be sending another in over the winter to duplicate it so I have a spare sitting here.