I think he had the potential to be great, but whether he would have reached McGrath/Ambrose levels debatable at best... he was a favourite in SA and Natal. Only played one or two seasons of county. And he didn't have the aura right from the beginning of his career. He never became a truly professional cricketer, I don't think.
Edit: I think when they compare to McGrath or Ambrose, they comparing style rather than he would have achieved the same heights.
Like a lot of cricketers then, they had to think about their careers outside cricket. Think he was one of them along with Irvine and even P Pollock that seemed to retire a tad early when you consider a lot of the guys we spoke about above retired late 30s and into their 40s. Rice was 45 at Natal I think.
Vince was actually chosen for the cancelled 1971/72 tour of Australia like Clive Rice
How good would they have become? The great question.
Barry Richards
Eddie Barlow (withdrew and replaced by Short but if things were normal I'm sure he wouldn't have had to worry about work)
Ali Bacher
Graeme Pollock
Lee Irvine
Dassie Biggs
Dennis Lindsay
Mike Procter
Peter Pollock
Pat Trimborn
Grahame Chevalier
(The newbees on the block along with Biggs who came in for Tiger Lance)
Arthur Short
Hylton Ackerman (World XI squad when the tour was cancelled)
Clive Rice
Peter de Vaal
Vince van der Bijl
It's something I'm trying to put together now in the SA Domestic History thread and using rebel series on order of potential new caps. There was more limelight on the 80s games but in the 70s lots of guys who didn't play in the 80s would have got caps like those above in reserve, Andre Bruyns, would they have gone to Lee Irvine to keep or Gavin Pfuhl/Tich Smith, Lorrie Wilmot, Donald Mackay-Coghill, Douglas Neilson, Pelham Henwood which Rhodesians (Duncan Fletcher, Brian Davison, Richie Kaschula, Paddy Clift etc)