Chevrolet: 1985 chev astro timing chain replacement, timing chain replacement, o clock

Question
hi roger i own a 1985 chev astro van 4.3l v6. my question is this, im in the process of changing the timing chain i have removed all the necessary parts to get to the chain an im down to removing the camshaft  sprocket and timing chain. my manual says the engine  should be placed at tdc on number 1 piston , then check the position of the timing mark at the crankshaft for 12 oclock. if the crankshaft is  not at 12 o clock the manual says to turn the crankshaft til the timing mark is at 12 , then loosen the retaining bolts on the camshaft an remove the sprocket an change, while making sure to leave the crankshaft untouched after setting to tdc. when i do this process i use the #1 spark plug as a reference with the plug removed i insert a piece of tissue in the plug hole as i turn the crankshaft with my socket at tdc #1 the tissue will jump out i know then the piston is at tdc #1 after i have to make a small adjustment on the crankshaft to get the timing mark to 12 o clock. once this is done with the small adjustment the camshaft sprocket is also at 12 o clock. the manual says i should then remove the bolts from the camshaft an remove the camshaft an chain, but also to reinstall the sprocket  and bolts so that i can turn the camshaft to the 6 o clock position to reinstall the new camshaft sprocket an new timing chain. this seem to me as thou it would throw the timing completely off. im shuned for what to do .

Answer
HI MICHAEL
     Well you have it all right so far down to the (TOILET PAPER ?) tissue, I would think all you should have to do is to align the two sprokets with the marks on them set them so they point at each other and if you are not replacing the cam- why take it out at all. you can put your finger over the no#1 plug hole while taping the starter a bit than it will pop your finger off when the pressure is all the way up on the no#1 cyld. than look at the timing mark and be shure it is all the way to top dead center. and the mark on the crank should be at 12:00 and the cam should be at 6:00 faceing each other than thats it, do not move them at all after that as if you are off even one (1) tooth you will be in BIG trouble.and have to take it apart all over again. so watch that the marks are perfect. and when you put the chain  on - first put the chain on the crank sproket than put the cam sproket on the chain than hold the cam  sproket w/ the chain in place than just fit it to the cams bolt holes it might be a bit trickey but you can do it. than after you get it in place make shure that the marks are all set right you can put a drop of white paint on each  mark so it can be seen beter so it will be in on the mark and still in T.D.C. than all you have to do is put it all back.but important make shure the marks are the same way as when you took it out. I would put a drop of white - I use typing correction fluid as it dries on contact. you have it down pretty good it is the marks that have you worried, well dont as all you have to do is mark them and put them in pointing at each other where thay are supposed to be. and you got it. OK let me know how you make out ok.
roger jm w.