hi, treez
here, I must say that the LT1006 is an op-amp and TL431 is a 2.5V voltage Regulator. You mean LT1009, I guess.
If you, then For TL431, it is very effective voltage regulator. As my opinion TL431 can be used in this circuit.
I suggest you to first practically run this circuit with TL431, I can say that you will not find any problem in TL431 instead of LT1009.
And if you mean LT1006, then I have no idea about it as the two parts are different. You should go for the alternative op-amps for that.
I hope you find the solution. I can be wrong. So look for the others suggestions.