[Bobboloo]

It varies depending on where you measure the cylinder but if you figure that the spigots are 97mm on a stock 2.7 then the math suggests that the cylinder wall is as follows at the base of the cylinder.

90mm = 3.5mm

92mm = 2.5mm

93mm = 2.0mm

There in lies the problem with the 2.9L conversion kit. 2mm of cast aluminum = not enough.

2mm of billet aluminum as in Nickies might work however.

Keep in mind that the cylinder is thicker at the top where compression is highest. You'll notice that the fins are wider at the top which also increases strength.