6 banger to a V8 frame question

[Mr.C]

I just bought a SWB frame that I was told had a 6 banger in it. After I removed the cab I notied that there were what looks like partial cross members in front of the tranny cross member. What are they for? Also what other issues will I have going from a 6 to a V8? I already have the motor mounts from my CST20 Longhorn what else will I need to keep from it?

Thanks, Mike