There is no lateral or front to rear play on the sub frame, only up/down adjustments.
The bolts that go in the rear of the frame have a conical shank that center the holes.
The frame may have shims at the bulkhead mounting, these are about 4x8 with 2 holes.
There may also be shims at the core support, other than these there isn't any other adjustments.
You cannot get the frame racked off the forward/rear centerline, the body bolts do not allow for that, totally self locating.
I'd drop the wheel liners with the frame or remove first.
I see no issues with dropping the frame and putting it back, just put whatever shims back where you found them.
Alan