Sounds like you have a dog that has real potential to work. I would give the pup a couple more months to, like to 8 to 10 months of age, before you start any real technical training.
If it has been on light cattle and done alright, keep it on light cattle. Goats and sheep can cause some real bad habits for dogs that will be used on cattle. They are low to the ground and pretty quick. This can cause a pup to "belly bite" on animals that are too fast. And then when they go to cattle and try it, they will get beat up.
The main thing to work with right now is obedience. Have a good stop or down on the pup before you start any real training. If you have that, you will have it made. Also make sure the pup will come back when given the command.
When ready to start the pup, get some light 400 to 600 pound calves. Three is the best to start with. Get them gentled down so the pup has some confidence when approaching them. You don't want something that gets too tough with the pup or runs off every time the pup is around. Even though the pup shows alot of strength, calves that run off and are flighty can lower the confidence of the dog. Try to use a small pen to begin with, like 40' x 20', or any other small pen you have. I like rectangular pens, but round pens are also just as good.
Start slowly, let the pup circle and bunch the cattle the first couple times you start training. And don't use alot of commands, if any at all except down or stop. Figure out how the pup wants to work, then start applying commands as needed.
I could go on and on, but this should get you started and thinking. Charlie Trayer has a real good book on starting dogs that I have read several times when starting a new pup. There is also one by Scott Lithgow that is a very handy manual, along with several others out there. Every time you start a new pup, you think you got it all figured out, then something new comes along. It's alot of fun when you know you have a pup that really wants to work.
Feel free to PM me if you have any questions. I love bouncing ideas and training methods around.