US Car Tool A518 Cross member

I saw this on the US Car Tool site, when looking at the 2004r mount.

67-75 A-Body 518 Crossmember Kit

I was originally going to do the 2004r swap, but I cannot locate a core and the rebuilt ones are expensive ($1700+) I don't need an all out race version, I just have a mild 340 and want the overdrive.

My question is, can I use this cross member for the A500? Not sure how much of a difference there is between the 500/518. I sent this over to US Car tool also.