There are many options and all are personal choices. Line dumping @ SSpey mentions is a concern. When creating and casting some of these type of lines many will find slowing down and opening your cast is the best in launching these lines.
There are many intergrated sink tip lines with heads from 15' to 30'. In my opinion these will cast better than most anything you could create in trying to replicating the same line.
You could also purchase a intergrated 250 or 300 30' grain sink tip head and personalize it by cutting away (back) until you find a sweet spot. For a 30' 300 grain head if you cut off 8' you be at 220 and 22'.
The current shooting set ups I'm running on my 6 and 8 single hand weights are the airflo rage shooting heads/ rio running line/ and I use poly leader sink tips and a couple lighter MOW float/sink combo tips. I can cast a variety of ways incuding using the double haul with no hinge feel. This set up does not line dump but actually lays out pretty nice for me. It can send the fly a long ways, but it also seriously limits your mending abilities. A sacrifice for distance. If mending is a priority i use a good floating line and with a poly leader (if i want to go deep) or a traditional 15' Sink tip 3 or 6 intergrated line.
After re-reading your post you are trying to use an existing running line. So ignore the above. Go for it! The worse that can happen is you don't like it. You might be better off trying to get a 30' 200-225 grain head tho. Help eliminate the line dumping.