The (official) chart is part of the SFC1 Patch 1.02 Supplemental Manual. It was released as a PDF. (I don't remember the link off hand, but if you can't find it, I'll look into my archives)
There are still impulse counts. It's just 1/32 of a turn now. There are several things that use impulse counts. (I can't recall an instance of a "single" impulse tho. Most of the uses go in groups of 4 impulses or 8 impulses.) For example ESG activation, Plasma's firing delay after launcher is destroyed etc.
All due respect. The best way is probably testing it yourself. put your self in an K-XCA, against a say F-POL. Then use the disprutor (which are faithfully one turn weapons) and timer on top of the screen to time them...