before you go putting all the good words together you should probably start with a goal of what you want to achieve. unless you go extremely serious, as in a motor that you would not want to drive regularly on the street then forged pistons and rods are a bit overkill. the a series motors are strong little buggers!

head work maybe some flat top pistons and carbs will all do you well.

not turbo n/a but dont want a14 or a15 to hard to get one so i am doin an a12 but is it worth doin it myself?

better to satrt with an a15, or even a14

Are you going to turbo?

If not, just use good quality standard ones with ceramic coating on them.

hey i am just bout to do pistons, cams, rods, valve all that sort of stuff to buil an awesome a12. dont no much bout doin it myself but want to try does has anyone done it and do you think it is to complicated to try never done this before so any advice helpful thanks