Donna,
I was thinking Blue also. Birchen Orps would work too. The first generation GLO x Brr would not show Silver laced but the second generation would start to show some. The other color I thought about was Columbian but that is just as rare as the SLO. I do know Corancher is working on Birchen Orps. I have a cockerel hatched from her eggs but he is Gold Birchen. I have more of her Birchen eggs in the incubator nor.
Either way, creating the lacing is a hard project with tons of culls.
Personally, if I were going to cross to another breed, it would be Sussex (white slin, single comb)
Just my humble opinion.
What color Sussex would you use? I have light and speckled.