Some of the best positions for larger babies are on all fours or an upright position as this gives your pelvis the best chance of opening wide enough to allow a large baby to pass through. Of my 4 babies I have had 3 large ones (4.18, 4.32 and 4.56 kg) and I birthed all of them on my back in a semi reclined position. It probably wasn't 'techinically' the best and or easiest way to do it, but that's all I felt like doing as it was how i felt the most comfortable. You may not feel like giving birth upright or on all fours, you just have to do what you feel most comfortable in or otherwise you may run into bother anyway kwim? And out of all of them my largest baby was the one that left the least amount of 'damage' LOL - I had only a tiny graze that required no stitching.

How well you fare out of it in respect to tearing has a lot to do with how the second stage is managed. If you have a midwife/ob who will let you wait for the perenium to stretch and if you gently breath your baby out instead of pushing then you should be able to give yourself the best chance of not having any tearing.

Grab yourself a copy of the pink kit - you will learn so much from it in terms of familiarising yourself with your body.