LsX sm465 2wd with factory ls parts 1967 C30

[gmc684x4]

From my research over this several times is the aftermarket Ls Old school style flywheel is needed then you can use any clutch kit that fits your arrangement

I have seen a few threads where guys use the Ls Flywheel with 80s clutch pack the issue there is it only has 80 % contact face to the clutch

here is novaks page showing clutch face differences

https://www.novak-adapt.com/knowledge/gm-crank-spacing