if you didnt line the timing set up before you removed it first thing is remove the valve covers and remove the rocker shafts ..this should be in caps ..i should put this in caps because it must be done before the crank is rotated without a timing set inplace ..or dont move a thing.. put the old timing set and chain back on and then rotate to the point where the dot on crank gear is straight up
then with rocker shafts removed rotate the crank until the keway points directly at the centerof the #1 piston (driverside head)
the keyway lines up with the #1 rod journal
from there you can find the true TDC of the piston and install the crank gear to see that the TDC dot is pointing up
line up cam gear to the bolt holes s and spin the cam so gear indicator is pointing straight down lined up with the crank gear dot
now slide cam and crank gears off put them in the timing chain so they line up the dots and then slide the whole timing set onto the motor , once you get the cam bolts in verify the dots are still lined up with tension on the driverside of the chain
if dots are lined up rotate engine twice and make sure they still line up at TDC , remove cam bolts apply locktite and torque the bolts to 30 lb/ft
if its a double roller chain that looks like a bicycle chain on the backside don't run the tensioner if chain gets a tensioner install it ,
if its a double roller and the chain has a lot of slack on passenger side you should surce the correct timing set , linebored engines sometimes need an undersized timing set
if its smooth back multi bar link chain like the OE then you should run a tensioner