well the way i sort have look at is if it has a sprocket for a chain whats stopping it driving a push rod camshaft rather than a over head cam shaft its not like the ratio's could be diffrent they have to be the same!
more to the point of the newer crank using a diffrent rear main and front main seal???????
sorry i thought they where the same ( i was wrong ) it's the ef one to use apparently.
we currently have a pair of 250's both with flat tops but one has the 200 rods (which are longer and changed the rod ratio) and the difference between to 2 is noticeable. so in the new one we'll use 200 rods.
from my expierence with holden 6's
the early motors have 9 thro cranks and the later ones have 12 thro cranks and the problem with the nine thro cranks is they are a un even counter weight because there is 9 counter weights and 6 conrods!
the 12 thro have alot better harmonics!
some people like the 9 thro cranks because they ar lighter so that they rev harder but this is not true because you engine wont rev if it has bad harmonics!!
12 thro is alot smother on the high rpms and stronger due to the harmonics and less vibrations!