timing
 

Speedy, not exactly sure how you checked your timing, but you seem to know what you are doing. I read that you had checked for TDC before putting the head on, which in my opinion is the most accurate way.
The way I have done it before is to have a degree wheel on the crank...a positive stop device bolted over #1 cylinder, rotate crank and mark on the degree wheel, reverse rotate and mark where it stops, divide by 2 and that should be TDC.
Having the stop directly over the center of the piston should eliminate most play.
I would think that belt elasticity and thermal expansion would have more effect than a small amount of piston rock, which if you can determine that amount, then it can be compensated for.

That's essentially what I did. Found where the piston just started to move on either side of TDC, and split the difference to mark TDC.

Got the engine in the car last night!
What's recommended break in oil and process?

I was just watching Ass Monkey Garage the other day and they ruined two completely different rebuilt motors by following improper engine break in protocol. Lesson learned from those 2 episodes; do not use break in additive, purchase expensive break in oil with as high a zinc content as you can find.

Fill with 20W50 and let it rip tater chip.

Any particular brand…? Non detergent or standard oil with zinc?

These aren't air-cooled airplane engines. You don't need straight mineral oil or anything like that. When I did my 968 rebuild break in earlier this year, I used standard multweight oil (I used Valvoline 10W-40 Premium) . I ran it an easy 500 miles. I drained the oil through a paint filter to see if anything was in the oil. I also cut open the oil filter to inspect the paper element. I expect you will see some tiny pieces of debris. This is normal.
Then refill with whatever oil you plan to run normally and as said earlier, let 'er rip.

Got it started yesterday afternoon! Time to finish bleeding the brakes, fix a little water leak, and get an alignment!

Congrats on the build! Keep us posted.

If you have questions on converting a 944S to a 968 driveline, let me know. Pretty sure I figured it all out; it's not rocket science!

Just an update- I played with my G-Tech Pro a little...
The last time I used it in this car with the original S engine, I got about 125hp.
New engine read 200hp... I put a new O2 sensor on the car after that too, since my gas mileage has not been what I expected, so I'll see if that made a difference soon.

The 968 motor gets significantly worse mileage than the S motor, I do 16/25 in my swapped s2. Your S will likely do worse since the gearing is a little shorter. My S gets 19/28.

I used to get 27ish on the highway with my S, but was down in the low 20s before the head went... I was looking for better out of the 968 between it's better engine management with the 944's lighter weight...

Nice work! Weight won't make much diff on highway mpgs. My 968 does 24.x mpg all the time (mixed driving). I've never done a full tank of lowish speed highway though. Speed limits here are 70 and traffic flows around 80...

And I've heard others claim 30 or close to it in there 968s...

it really depends on speed. at 55, you can get over 30 in a 968. at 65 you'll get about 27. at 75 it's down to 25.