Quote Originally Posted by Matt Rowe View Post
This doesn't change the real vs fabricated model debate but did we drop the part of the UD/BD rule that requires updates as an assembly? If not that precludes the idea of early block with later internals.
No, in 1987 3 rib (early) blocks were sold with 21mm gudgeon pistons, and associate rods and crank. The motor did exist, the chassis stampings and brakes it would have come with were pretty specific, though. Late chassis, late front brakes (22mm wide rotor), early rear brakes, late body details.

The point is that if we allow this, and we have for years, we allow this. It can have effects that are simply trivial, like the mr2, or maybe that create better than expected outcomes.