I overheated my 22re and have since had a rough cold idle and low compression (115 psi) across all cylinders. The coolant in the reservoir smells like exhaust or fuel. No fluids mixing or smoke. Engine dies at cold idle unless I give it gas. Sounds like a head gasket or possibly an intake/exhaust manifold. Is there any kind of head or intake exhaust issue that would cause low compression across all cylinders or is it safe to assume the rings/bore are significantly damaged to have such low readings? I put oil in in the lowest psi cylinder (at 105 psi) this was the only cylinder that wasn't at 115-120 psi, and it shot up to 170.

 

Low compression is either valves out of adjustment, failing piston rings, headgasket failed, or timing way off.
A wet compression test wouldn't help if it were valves, timing, or headgasket.
My guess would be the pistons and rings got hot enough where the rings lost some of their spring tension.

Some of the parts stores have an inspection camera/boroscope in their tool loaner program. you can remove a sparkplug and run the probe in to the cylinder and get a visual on the piston walls.

The most common scenario is the headgasket failed, too, allowing hot water and steam to enter the cylinder(s). The hot steam would remove the oil film from the piston walls and the rings no longer had any lubrication as they travel up and down, resulting in vertical scoring on the walls. But your compression numbers would seem to indicate the headgasket stayed mostly intact.

I'd probably still recommend the block test. As much as I recommend a leakdown test I'm not sure you'd learn anything more at this point. The reason for the block test is if it fails you can start scrutinizing the old headgasket looking for a failure, hopefully finding something to explain the overheating event. If it passes the block test you can fix the engine but you'll still need to find the root cause.