Several moving parts here. Have you created the vIST between the two 7200's? Are there any vlan IP addresses that overlap between the new and old core? Using the fabric with the vlan's/IP's added to the GRT, that should all ping normally. Assuming no overlapping IP address, and reasonable subnetting practices, the fastest way is to add static routes to each side of the interconnect across what I assume is the /30 or /29 mgt IP. You will have to add a static route redistribute command on the 7200's so the GRT learns the 5530 side and vise versa.
