18 spline A body 4 speed

And what makes you think it will be any better with a larger input. Most failures are caused by improper clearances , installation or the one using it can be the culprit also. Center line of bell to crank? We already tried breaking a 23 spline in a 70 Roadrunner. Had someone in the back ripping 2nd without the clutch flat out on throttle with the big long pistol grip and then kicking 3rd. We kept doing it over and over until the 3-4 linkage arm bent.

You broke 3 you have issues I never ran into. The issues I saw with my own eyes was two 855 18 splines from Passion burnt blue inside. Had nothing to do with Power or abuse just not assembled or installed correctly. Maybe Jamie would chime in and let us know what went wrong with them. His friend was here yesterday. His Hemi 855's are out of stock. ?????
I definitely think it's my clutch setup but why does Brewer's try and tell me my 23 spline is only good for 450hp? They were more or less pushing the 18 spline.