I really like MGS epoxy for vacuum bagging, has 4+ hrs. working time and great properties, used for full sized aircraft. Mixing ratio is 100:40 by weight. A good layup is supposed to be 40% resin by weight, but is almost impossible to attain. Still good but more practical is 50%, so I shoot between the two. With the cloth weight per square yard you can figure the weight of cloth used and you need an equal amount of resin for a 50% layup.
