timing issue

[camjck89]

hey guys can anyone give me instructions on how to properly install my hei distributer. i have put it in exactly like the old points system and done everything but wire it, however im being told that it may be off 180 degrees and the timing chain might go in it . what im wondering is how do i fix it with out making it go "boom". i dont know alot about timing and getting the engine at tdc and all. ii just figured as long as its in like the other i could just tweak it to make initial and total timing correct. if anyone can help then id appreciate it