Hi Andrew. Interesting challenge, splitting a single request into both a Project and a Task (for custom data). And yes, I can offer a solution.
A few months ago, we created a (private) module for our "http://store.atappstore.com/product/ubercalc/">UberCalc engine that allows Workfront SysAdmins to define a subset of Custom Data at a parent level (Project, in your case) and have it automatically push down to a child level (Task, in your case) in the background. If I'm following your logic, this would allow you to convert the Issue to a Project (with the Resolving Object the way you want), but have some (or all) of the custom data then automatically push down from the Project to the Task(s) of interest.
For background, for The Curious, the original usecase was to allow Marketing Teams to control certain information at the Program level Brief and have it push out (and override) the Program's current Project level Briefs, on mass: think "breaking news". Worked slick!
Regards,
Doug