I agree with your thinking about the need to adjust the parts.
In general I find that most parts I get these days are replacement parts, not reproduction. The difference in my mind is that reproduction parts fit without re-work.
Yes, I'm with you on that.
Then again, I've had mechanics who were working on these old trucks when they were new tell me the OEM replacement parts had the same problems. haha.
I finally got it to act right using a wooden board and some well placed blows from a hefty sledgehammer.
Not how I prefer to do things, but I was running out of options.