Hello , Mommytana . Welcome to our world.
And yes, you can cut the Brisky in half . It will then cook in approximately 7to 8 hrs. , however that is subjective to a lot of variables . Cooking heat, Weather , amount of fat on the Meat (can be lessened to reduce the Smoking time - but leave some for moisture .
Put a good 'Rub'on it (I like to use simple S/CBP ) . Hard to beat S/P ( Beef seems to need a good amt. of Pepper and the Salt helps in Smokering production when you use chips/chunks/sticks ( cut to smaller sizes).
Expect to have a long cook , you never know how the Meat will cook. Start earlier and if it gets done sooner than you need (the same day) it will hold in Foil and a large towel and placed in a cooler to rest and finish cooking.
Have fun and . . .