Sounds to me like you would be XL in most Firstlite, maybe large in the shirts and coats depending on how you like them to fit. I'm 5'10" and 175 lbs and I order everything in a medium.
I'm 6'2 and about 240 lbs. For Kuiu, I wear a 38 in the Attacks and Tiburon pants. My chest measurement is about 49" and I wear an XXL in Kuiu jackets and tops. The FL stuff I have is mostly XL with the exception of their Llano top which I wear in XXL.
for kuiu its pretty true to size for me. im 6'0 220 and wear xl shirts and wear xl in kuiu baselayers and it fits me good. i wear 38 in shorts/jeans and 38 in tiburon pants. i dont have kuiu jackets or FL base layers but i have 2 FL jackets (Uncompaghre/boundary stormtight) and they run a little bigger i wear them in a large. i probably could wear an xl thought if i wanted a little baggier fit.
I am just under 5'10" and weigh 200 lbs. and have the same waist size as you. My XL First Lite Kanabs fit really well with a little room in the waist for layering. The length is just a tad bit long but works well with my hunting and hiking boots.