2.5 vs 2.7 block

[320smithy]

I am looking at building a 2.7 or 2.8 and I have both a 2.5 and a 2.7 block to start with.

The only difference between the two I can find in my research is that the 2.7 is 0.5mm higher.

Is that the only difference ? any preference in which one to use ?

[reggid]

both will work, b25 block is better for clearance than the early ETA blocks for clearance but its not insurmountable.

the 0.5mm difference in deck height is a myth, the 0.5mm difference is the stack height difference

some of the early 2.7L block have a huge welsch plug at the back which some might see as weakness to the block or another source of potential leaks but i would not be worried

http://www.r3vlimited.com/board/showthread.php?t=285315

note that the crank used in the link is the US spec crank so the webs are bigger and the issues shown with the big counterweight crank will not exist with the "correct" 2.8 crank