BBC vs. SBC front springs

[my67chevytruck]

curious if anyone knows the height different in the two springs due to different spring tensions in the two. I left the bbc springs in the front when we installed the front end from the donor truck. I need to bring it down some more, but curious what the standard sbc springs would do drop wise, so i could go from there. I am thinking i need to get it down another two inches. I currently have ece 2 1/2 drop spindles and the stock bbc springs.... I am thinking the truck would drop about an inch if i switched to the standard sbc springs. I will look into a 1 - 2 inch drop spring. just wanted too see if i was slightly on track.

Thanks