Who has the rundown on the evolution of the LA series engine?

I’m curious about the mid to late 80s, specifically.
As I recall, there was a time where the engine blocks had the taller lifter bores but still has flat tappet camshafts. Those blocks could use flat tappers or roller lifters. At some point, the engines went to roller camshafts and didn’t go back.
The MP crate engines were based on the 5.9 series that were built with roller camshafts originally but did the crate engines also have roller cams?
Thanks.