I guess it depends upon what you mean by "okay." Assuming N is large and even it will replicate the expected bits overall, but you do have a deterministic element in your generator. As such, your runs should be off.
There are two alternatives. The first is to buy a four sided dice at a game store. The second is to roll the six sided dice twice if the roll is a five or a six. Then on a roll of 1,2,3 it would be the first set of bits and on 4,5,6 it would be the second set of bits.
If you are trying to replicate four possibilities on each roll, with each having the same probability of happening, then on a per roll basis you it is not okay. If you are only concerned with the proportion of bits and n is large enough, then this would work as an approximation.