As long as the total weight of flour is the same you’ll still get bread no matter how much you much you change the ratio of white/wheat/rye flours. It will taste different and have a different texture but it will still be bread.

This recipe in particular is something like 90/10 white to rye so it’s basically white bread with a little rye for a more complex flavor. 90/10 white to wheat is going to be pretty similar.

I’ve got 2 different starters, one on wholewheat and the other on whole rye. Since both flours are wholegrain they grow just fine and are fairly similar! In terms of the final bread, I think it will be very similar if you just sub the rye with wholewheat. In fact I completely agree with all the others who’ve said exactly that. And, I must also agree that if it is less than 10% rye in the final bread, it is quite difficult to taste the rye.

My starter was made with unbleached white, non organic flour and tap water, is maintained on the same, and works for all bread that has some amount of wheat flour, including the one that is 60% wholegrain rye.

Levain is simply big starter - I always make it with unbleached white flour no matter what the recipe says.

For the actual bread, I’d sub whole wheat flour but watch it, it will rise faster than rye.

In my experience you can make your starter from any flour, it will work, but using other than white wheat flours will produce a tastier loaf. I generally use a mixture of wheat and rye. The recipe calls for pumpernickel or rye so just try rye. Besides, there is only 53g of it to 630g of wheat flour, your spouse won’t even notice.

Rye flour in American recipes doesn’t do anything. Replace it with any wheat you have. 53g for a loaf won’t make any difference.