AZTman you nailed a lot of things.

I would check the length of the pressure line. I have heard that you want the pressure line to be half the length of the fuel line. If you pressure line is too long it won't provide good pressure and you will see air bubbles in the line.

How did you test your tank. You should dunk it under water as well to check for bubbles its also a good idea to run a bead of CA around the tank seam.

The 5 port tunes a little different then the 7port and likes the bottom end to be a little on the rich said compared with the 7port.

I would be sure and seal the carb anyways, when the engine is cold it may not be leaking but when it gets up to temps the expansion could cause a small leak. I would also check the throttle boot. People don't realize that the boot is an air tight seal and a pinhole in it would cause an air leak.

Dotan the head shims will help with this, the majority of piston breaks are user error and not a defect (I am not saying yours was user error just crunching the numbers I have seen) . It occurs almost always in the 7port and is the result of overreving the engine too soon in the break in proceess or not making sure the engine is placed at BDC as soon a it is shut off.

Adding a head shim at the factory will soften the compression during break in and help with this, also trying to inform the customers to not rush the break in is very important also. Trust me when I say the actual failure rates are very low but in this day and age. When 1 engine breaks on the wrong person and that person goes and blames the factory online you will have thousands of people questioning the quality of the product (people who are anxious for the sightest flaw to reasure themselves that there $300+ engine was worth the money) It is better to also have the engine over shimmed for race conditions then to expect a customer to have to go out and buy a shim with there brand new engine. You can always remove the shim but I would wait until the engine is fully broken in around the 1 - 1 1/2 gallon mark.