Try this - edit the draft and put it in Fiberworks, Weaveit or draft paper to make sure it will work - I haven't done that and I'm not involved in the creation of the JST patterns - so don't blindly trust what I've worked out 😏. However, I have adapted patterns to work on my looms, but PLEASE check it yourselves to make sure it works on your looms. Don't take my word for it. Basically, you'll be missing that last segment of the gamp but maybe you could design and weave a scarf using that portion. Anything is possible.
Go to the top row of the threading and remove 1 repeat of each of the multiple threadings in that row. The first repeat calls for 8 repeats - reduce it to 7 repeats, the next repeated threading calls for 7 repeats - reduce it to 6 and the third repeated threading calls for 5 repeats - reduce it to 4. In the second row - go directly to the 5th 3,3/1,1/3,3 segment on the end and replace it with border segment of 4,3,2,1 x4. The majority of the 3rd row of threading is no longer in this sample. Don't forget your floating selvedge for weaving twill. Your total would be 309 ends (including floating selvedges but double check my math ;-) You'll have 26 inches for your width in reed.
Please don't take my word for it and double/triple check it yourself. As I've said - I'm not involved in writing patterns but this would be one way I might adjust the pattern if I was doing it on my table loom. Hope this helps and this is an unusual situation with a wide sample using a heavy yarn.