struggling to find injector specs - still learning not sure if I'm correct or not?

Hi All , I have the astro up and running with the vortec heads and marine manifold , tweaked spark table using Daves vortec table and although running its not quite right and seems to backfire in inlet if pedal pushed too quickly , wondering if I'm correct that injector offset vs voltage will also need to be changed as stock values were for cpi and now batch firing 24lbh mercruiser injectors but fpr set at 3bar, any advice appreciated

Thank you