Daryl, sorry now I am a bit confused - Usually hemi/6 pack 833's have 18 spline transmissions, others are 23 spline, TKO's or many modern transmissions have the 26 spline input shafts. Correct, you cant mix them due to the spline count. So which transmission do you have?
If you have a TKO, you have a 26 spline - 18 will not work. Again, issue is the size (143 is larger) to fit inside the scatter shield. My small block (hemi 5.7) only allows enough room for a 130 t flywheel.
Apologies, I may have missed the initial question, but bottom you can generally mix and match some items, but concerns will always be size, balance and spline count. Being I have a 130 flywheel 10.5 flywheel with a GM 26 disc and pressure plate, no issues. (Summit has them on close out for very cheap many times)
Hope this clears it out