wwall: Instead of 28...Bc6, Ivkov said that no good was 28...Rc6 29.Rxc6 Bxc6 30.Rc1 wins at least a piece (annotated in Chess Life, Feb 1969). But after 30.Rc1, Black continues with 30...Bd8 31.Qc3 Bb7 32.Qxe5 Qd7 and White doesn't win a piece. I think that after 28...Rc6, best for White is 29.Ra1 or 29.Qa2.
Instead of 31.Rd1, Ivkov said better was 31.Qc2 first, then 31...Re8 32.Rd1.
Ivkov said that 31...Re8 was the wrong move and that Black should have played 31...Ba4 32.Nxc7 Bxd1 33.Qxd8 Rxd8 34.Nxe6 fxe6 35.Bxe6, with victory a long way off. It would seem that 35.Bxa6 would be stronger since White threatens 36.Rb6 and Rxe6.
Instead of 32...Nh5, perhaps Black can resist more with 32...Bxd5 33.exd5+ Kh8, or 32...Nd7 33.Nb4 Qf6.
Instead of 33.Ne7, White could also play 33.Nb4 Bd7 34.Bxf7, threatening rook and knight.
After 33.Ne7, Black would play 34.Bxf7 Rxe7 35.Bxe7 Qxe7 36.Qxc7 Qxf7 37.Rxd7, winning the exchange.