Average difference in injector pulse times (ms) between B18A vs B20B.

I am just trying to get a rough idea of what percentage I should use when building a basemap for a B20B I put in my 93 RS. I see the fuel multiplier and have been getting lean results from just switching from 1834cc to 1984cc which only comes out to about 7% increase. What has everyone else used on when creating yours? If it helps I have I/H/E and a P8R-8 head. I just figured out why my low RPM tip-in was so jerky, I had it way too lean for initial tip in I guess. I changed my idle-1500 injector (ms) up 45.