Check out the American Rhododendron Society plant finder.

It is best to stick to a hardiness of -15F for Zone 6. You could try to -10F.

It looks like the best tall pink is Lady Eleanor Cathcart, English Roseum, or Mrs. C.S. Sargent.
The best tall lavender is Catawbiense Grandiflorum, Parson's Gloriosum, Roseum Elegans or Roseum Superbum.

Here is a link that might be useful: ARS Multi-Parameter Search for Rhododendrons

Thanks.
I'll see if I can find them in my area!