So I put a new motor in my XJ. It started last wednesday, but had to shut it off during the cam break in (heard it was fine to do that), because I had a transmission cooler leak. I was 7 minutes into the break in.

So friday, went to the JY and got a "new" tran line. Went to start it up, and it won't start now. It cranks but won't fire up.

I tripled checked all connections/vacuum lines, checked "timing", checked fuel pressure, checked spark, replaced the coil anyways, replaced the CPS, and replaced the engine ground with a 4 gauge wire (sanded and cleaned contact points).

I'm stumped.

So you do have spark? How about fuel pressure?

Yup. I've got spark, and fuel pressure is at 31 psi with key on and engine off (obviously cause it wont start)

None of my wires are grounded out and all connections are in the right spot.

Could it be the grounds on the dipstick stud? I didn't clean those because I didn't think they would have anything to do with it not starting.

My "quick check" for grounding issues is to take a set of jumper cables, clamp on to the battery (-) and the engine block. See if anything changes.
Are your plugs coming out wet with fuel? Can you smell gas?

If you have a verified 31 psi of fuel pressure and you have a strong, blue, snapping spark......(you state you have both), the next thing I would suspect would be the camshaft position sensor located inside of the distributor.

Can be tested with a meter and a manual.

Good luck and keep us posted.