When I was using resin, I ended up with close to a 100/50 cloth/resin ratio. This was achieved using the slow hardener, making sure cloth is properly saturated with resin but with as little excess as possible, a good vacuum, perforated release film and a minimum of two layers of breather cloth.

Prepreg is around 100/38 to 100/42 depending on the make I have acquired, so I doubt that you could get it much better than 100/50 in a DIY setup.

Assume 100/60 and you will probably be slightly over. However, this is only my experience and results, other experiences and results may vary :-)

You could make a simple test piece to see what your setup and technique gives you.