I will admit I got suckered into buying crap parts because of price.
But I learned.
I bought a manual flywheel from CAT about 20 years ago. No one I know could figure out what bolt pattern it was drilled for... I looked at Ford, GM, Jap cars, Studebaker, Hudson...nothing matched. So I bought a Hays and it fit.
I wound up having the crank bolt holes plugged and had it redrilled for an 8 bolt early Hemi.
Then I bought a set of block headers for my 354. The flange was warped so bad my machine shop could not machine it flat unless the middle of the flange was ground to about .040 thickness from its original .125.
No more.