Long, bare branches on pines is a real problem because they are reluctant to back bud on bare wood. You are also limited by the scots pine being a single flush species.
There are no short term solutions but there are a couple of possibilities.
Try to chase foliage back toward the base by encouraging back budding: Feed and allow the tree to grow freely for a year then cut all growth back to the oldest needles. A really strong pine that is growing well will grow new buds in the remaining needles but will usually also put out some emergency buds on the bare sections
Allow them to grow freely to strengthen then prune back to the lower or suitable ones and repeat until you have what you want. This is not without risk and can take 10 years or longer just to get to a more suitable starting point. You will need to check on specific timing for cutback to get best results.
Remove the longest, usually thickest, branches to get live growth as close to the trunk as possible with existing foliage. Wire and bend the remaining branches to compress the tree and bring the existing grow points closer to the trunk. Then grow the result to get ramification. Some of the bends can be hidden with foliage, some can become part of the design - contorted growth tree style? This method is quicker to get started but not always very attractive. Some skill required.
Graft: Longer branches can be bent around so the growing points can be approach grafted onto the bare sections in appropriate places. After the grafts are healed grow the result to create the new tree. Approach grafting is the easiest to do but still requires some technique. It may take a few years to get enough successful grafts to start work. Pines can also be grafted in the traditional way by removing scions and placing them where required. This is neater but requires a little more technique.
Kirky's idea of literati was also my first reaction. It will be the quickest but literati is not easy to do well. I keep looking at the right branch - following the front fork as it appears to have the best possibilities but not sure what is above the first couple of forks.
