i have a few questions for all u guys
how much car you take off the head?
how much can bore it out ?
what is the best cam specs for a rally car?
if anyone can help much aprecated.

I'm having one bored out to accept A-14 pistons. It is going to yield about 1300cc. I'm not taking anything off the head as it is going to be a turbo engine so I can't help with that part.

i thought all the a-series motors have the same bore just diffrent stroke, but you say youre boring out to fit a-14 pistons? have i been mislead somewhere?

The A-12 has a bore of 73mm, the A-13 has the same bore but additional deck height of 15mm. the A-14 ande A-15 have a bore of 76mm and the tall deck height. To make matters worse, the A-12A has the same short deck as the A-12 but the bore is increased to 75mm. All of the engines, other than the A-12, have the distributor near the middle of the camshaft. The A-12 has it up front by the oil pump. Hope this helps.
By the way, I'm not just a know it all, my new Nissan Motorsports catalog just arrived and I'm quoting it.
Also, I'd like to throw a big "Hello" out to my grumpy old buddy George Ward. Thanks for lurking on the site. Why not join in on the fun? It's free!
I can't spell sometimes, sorry about that George.

my old motor had the distributor in the middle and it was an a-12 out of a 120y i thought, is that possible or must this motor be something other than a-12

That would be the A-12A. Here in the US, that was only available in the 210, chassis code B-310, from February '78 to January '81.

I have 3 A12 engines (1 in the car and 2 sitting in the corner of the shed), and all of them are out of 120y's and they all have the dizzy in the middle of the block.