I am not sure where you could get more info on VB after a 3rd degree tear except for your Obstetrician or Physoptherapist. Your going to find info that supports both VB and C/S in that also.
There is no reason why you would have repeat trauma to the same degree with no2 especially when its unlikely you would need forceps again which was probably the biggest contributor to the 3rd degree tear. With forceps you also have an episiotomy most of the time which also contributes due to an extension of the cut.
I would go with what you want. If you don't want to risk further trauma then the C/S would probably be the answer. Unfortunately even with great care at preventing reopening of prior trauma there is no guarantee. In saying this of the third degree tears I have seen go on to have VB I think one was intact peri and the others were 2nd degree tears.
Also with C/S they do cut straight through the pelvic floor muscles which weakens the bladder so having a C/S does not safe proof you from incontinence although that is of urine.
Its a tough one but I am sure you will get the support in which ever birth you choose to have. Also if you go for a VB I would make sure you have an experienced Midwife or Obstetrician assisting with the delivery as it does make a difference when guiding the head and shoulders out in preventing trauma (over a student for example)