If you've changed the chain and the crank hasn't been rotated at all, the timing marks on the sprockets will be facing each other.
When they are aligned like that, although #1 is at TDC, it is #6 that is at TDC on the firing stroke.
If that is the case, rotate the crank a full revolution so the timing marks align again, and the #1 will be at TDC on the firing stroke.
If the crank has been turned, and the #1 spark plug hole is in accessible with your finger or thumb use the #2 spark plug hole to feel for compression as the crank is rotated.
When compression is felt on #2 rotate the crank the 2/3 turn it needs to get the timing marks lined up, and #1 will be at TDC on firing stroke.
With that done and distributor aligned with #1 HT lead position the alignment hole should line up.