A pension or retirement account can't be used for retired clergy housing allowance unless the plan is sponsored by the church or denomination. Generally, a church would provide a 403(b), a section 457 deferred compensation plan, or a traditional pension.
If you were to roll the funds over into an IRA in your own name, you lose the ability to treat it as a non-taxable housing allowance. The retirement plan must be sponsored by the church or denomination and the housing designation must be made by the church or denomination.
But what specific investments you have within the fund doesn't matter.