Timing question on I5 10V hydraulic lifters

[Carl & Dawn]

Hi all,

I have a new set of lifters in and the Blau sport 272 cam is in place, I
just have a few minor things to button up.  I have a qusetion about the
timing though.  I had the timing belt done a few years back at a
supposedly reputable shop and the car had run fine since.  I noticed
that on the cam gear, there was a mark on the engine under the upper
timing cover, it is at about 5 o'clock.  As I spent a large amount of
time getting the mark where it belongs according to Bentley, I noticed
that the lobes of #1 were not BOTH pointing up, the first sign of TDC -
verified by the rotor position, crank pulley, or flywheel.  TDC was only
accomplished by lining the cam gear mark with the mark made under the
timing cover (I used the rotor position method)  Is it possible that
indicated TDC can shift to another cylinder and still have the engine
run properly?  I suppose that in theory TDC could shift to #3 or #4
cylinder and the engine would still run with everything off 180 degrees
as long as the distributor was positioned properly.

Does someone out there who has done this a lot have a quick method to
make sure you are at TDC for #1 cylinder?

TIA
Carl