Hi! I wish you the best of luck, how great that you've found something you're interested in!
Now, first off; in my honest opinion people obsess too much over the breed of a dog. Any male dog is fine, as long as he's interested in you and able to mount. You should find a breed of dog that fits your lifestyle, or visit a zooey friend who already has a dog who is known to like to mount.
You cannot force a dog to mount you and the first dog you get might not mount you anyway. You have to be invested in just owning a dog in the first place, and have appropriate amount of experience with training them, too.
A labrador retriever is the 1# most popular dog breed in the world, and no wonder, they are easy-going, easy to train and generally have low aggression. A malamute will require high amount of work and exercise on top of a lot of dog-knowledge. It's not an ideal first dog.
Most dogs I find sexy, like rottweilers, pitbulls, hunting dogs, kangals, cane corsos.. they are very hard ones to keep. They all need either special circumstances (goats and land for kangal, no other dogs for pitbulls, a lot of exercise and all members of family good with hardy dogs etc..) or a lot of activities to keep them from getting bored and destroying the home.
So, when you find a dog who will want to mount you, you have to be ready for it. You should be able to take a dildo the similar size of his knot so you won't hurt yourself. A dog does not work like humans, too.. they don't get hard first and then insert but instead push their non-hard penis inside with the help of the penile bone, and then start humping away and swell while already inside. So he won't tear you on the way in, and you won't be able to assess if you can "take him" while he's humping you, but when he's already inside and that might be too late..!
You should see his penis first by masturbating him or catching him when he's hard inside the sheath (some of my dogs used to get random boners when something exciting happened like when I woke up, when we played, when we were going for a walk.. it happens sometimes) to assess if you could take his girth.
So, anyway, the most important thing is to get a dog you want to live with for the rest of his life, and then get experimenting. Don't rush into it! My first dog was a tiny lap-dog unfit for sex but I loved them so much! And still miss them! My sexual experiences came much later and were worth the wait.