in 23 years of building & moding a series i have never had a a12 do the bottom , but since 1990 when i got my first a14 pulasr twin carb import have done 3 cranks on no;3 yes all 3 on no;3.by the way the little roofer got pushed alot harder in the rev department.... p.s got 27 plus years of eng building & moding exp.. on lots of diffrent eng's. in my opinon the a14 is best for moding but a12 like i said revs quicker & harder..[less reciprocating weight & shorter stroke add's up ..hum interesting hey.] opps just remebered i did when i was 19 did rad cooked her & seized.when comming back into town from work.waited untill she cooled off & restarted did this three times to get home.

There are quite a number of our members, & an awfull lot who are not members who have tested the A14/15 bottom ends to the limit using cranks that are not cross drilled & these engines have not been found to be wanting.

The reliability of A series Datsun bottom ends is legendary, to the point that, for many people, they will swear that as long as there is oil in the sump, you can't kill it.

As for being 'quick to rev', I think that, in stock trim, the torque from the half inch [12mm] stroke increase in the A15 will cancel out any problems there,
In race use, the A14/15 doesn't take a back seat to its shorter stroke brothers & many have come back from a 10,000 rpm wring-out to live & tell the tale. [then again, a few didn't. LOL]

just read some more post. in my eng's a14 & a15 don't seem to be as strong in the bottom end unless you cross drill crank nor as quick to rev neither as a12's .just fitted a12 to swb 4x4 serria 81 1lt model ,eng mods as said in post has 30/70 cam to might go back to su's for 4wd i run a 1974 leyend marina x low rad[aust model]. good for 8000 dosen't start untill about 4200-4500,"littel roofer". street driven sorry made mistake should have went to building a series new at this never to old to learn