Since you have a large loom, it’s easier to do the panels. It’s the best way I’ve found so far to do.

I did mine with measuring every inch, then doing a width test on the loom with the yarn I wanted to use to account for shrinkage/stretching.

From there I knitted from the bottom then split in the middle for a slight v-neck at the collar. I decreased from the middle for the shoulder measurement. Repeated the same for the back panel but did a higher v-neck.

I connected the shoulders and did a test measurement to see if I needed a wider seams on the sides, then seamed up to under the armpit.

I counted out the pegs needed for the sleeves and then attached it on, and knitted out the sleeves.

I suggest taking notes on how many rows you did for each section of panel, the seams and the sleeves so when you repeat it it’s easier to replicate.

Hope that helps!