Injector pump timing

Ok, so I have a Ford 7000 that I am about to change out the Simms injector pump. The procedure for this tractor is to line up a timing mark on the flywheel with a small inspection port on the bell housing (with the #1 cyl at top dead center) and have the pump on the #1 cylinder when it is bolted on. My problem is: I cannot find the timing mark on the flywheel. I know there is one because I found it 20 years ago when I installed this pump. I have rotated the flywheel tooth-by-tooth with a screw driver until I am blue in the face and cannot find the timing mark.
So I am wondering if there is another way to get the timing right? Like maybe just making sure the new injector pump is lined up just like the old one when I take it off? There is a slot in the tach drive shaft on the pump that is used to set the pump position and a tool to ensure alignment of the pump. I am going to try again next week to find the timing mark on the flywheel but I am not confident I can find it.
Any suggestions?

Narrow it down a little by getting it into TDC on #1 first, then looking for the mark. Take the valve cover off, and when the back cylinder intake exhaust closes and intake opens right away, that's close to TDC so #1 will be TDC on the compression stroke.

Remove the side cover on the pump.. rotate the engine in the normal direction of rotation.. THATS VERY IMPORTANT..
Just bump the engine w the key to find rotation..
Now rotate engine until #1 tappet IN THE PUMP JUST STARTS TO RISE..
THAT MEANS your on #1 compression..
Remove the cover at the front of the engine, directly in front of the pump..
There’s a timing line on the pump drive gear and a boss on the pump w a timing line on it.. u just line up those lines.. about the 12-1:00 position.
U said u were swapping out the pump.??
MAKE SURE the mdl #’s are the exact same.!!
THATS VERY IMPORTANT..
The tag is between the lines and the side cover..
Just because they “look the same”
doesn’t mean a damn thing.. lol

Thanks, pumpguy, that sounds like a good procedure to use.
The old pump is a Simms with a tag: P5147. The rebuilt pump I bought is a MINIMEC with tag: P5147/4.
I don't know the significance of the /4 on the new pump. Think that will cause a problem?

To late to give a damn now ain’t it.?
Lol

To late to give a damn now ain’t it.?

Well that was a snarky reply and was no help at all. Thanks anyway.

But the rebuilt pump is now installed and the tractor is running good.
QED.

Lol.. my point being, u already bought the pump and in the process of installing it..
It wouldn’t of much mattered at this point, u would have installed it anyway..