For comparison, stock timing on an A55 is 140 exhaust, 100 transfers, and 120 intake. Also it might be hard to cut 3.7 mm down on the intake side, so you can also just cut the piston skirt up on the intake side. Cut the intake port down as low as you can manage to do, then cut the difference out of the piston skirt. You can do all of this pretty easy with dremel bits and some time. Nothing crazy, just measure and you will be fine. But measure often, going to far makes it hard to come back.