Along the same line as you are doing, I now have two full sisters that are half beefmaster and half wagyu. One looks like a black beefmaster and the other looks like a black wagyu but not as ugly.
These are first cross Beefmasters and in due time I will upgrade them to a registered Beefmaster.
I am just hoping I can maintain some of the Wagyu carcass marbling while making a real good beef mama cow with the Beefmaster influence.
Anyone interested in Beefmasters can go to www.beefmasters.org
for more information.