I'm going to play devil's advocate here and suggest that maybe, just maybe, there was no shoulder dystocia at all and this was your Ob's lame ass excuse to needing to hurry up and get bubs out of there instead of giving you more time to push. I say this because you DON'T use forceps to pull out a baby with shoulder dystocia!! When I read that I felt sick thinking about what could have happened to you or to bubs if the reason for forceps was shoulder dystocia! He could have done a lot more damage than leave a small scar (which in itself should not have happened!). The other thing is that bubs had a large cone head. The moulding is indicative of your baby's skull needing to mould to fit through the birth canal and this is entirely normal for this to happen and also the reason why you had such a long pushing stage - again it is absolutely normal for some women to push for that long with absolutely no risk to the baby. For my first birth I was pushing for 1hr20mins and when he was born the moulding on his head was spectacular - it was a sight to behold that's for sure! But, he had a large head. At birth his HC was 35cm, but a week later it was 40 - after all the moulding had gone and he had a beautifully round head.
If it were me in your shoes and the Dr did that to me. I'd be running a mile quite honestly. I would be concerned that he chose to use forceps instead of one of the acceptable manouvers to help bubs out and it would indicate to me that he either does not know how to perform them or that he's just an ass who doesn't give a **** about what happens to his patient. I've had shoulder dystocia with my last two babies - both of them were in a terrible position for birth and both of them were born without the use of forceps. For my last birth the shoulder dystocia was particularly bad because he was born with his head in a deflexed position and his back was along my left side, so his shoulders were in a north/south position. My Dr use the McRoberts maneuver to get him out with no effects on bubs at all.
Please consider getting a second opinion or changing care providers. There is more chance of the shoulder dystocia happening the first time because bubs was in a bad position as opposed to anything being wrong with your pelvis. This is also your second birth and a completely new baby, so the chance of it happening again is quite small really and certainly nothing to warrant an automatic c/s for. Put it this way, you could be choosing to have major abdominal surgery that comes with its own risks and healing issues to prevent something which may not happen again.
So ask as many questions as you can, check out spinning babies and work on optimal fetal positioning and give both of you the best chance of it not happening again. Even looking into getting the pink kit to help you understand your pelvis.