Not sure I follow you there. High crankcase gas pressure like blowby or is coolant leaking into the engines crankcase mixing with oil (it'll look like a milkshake if so)? If you have a bad headgasket, it's leaking coolant somewhere or you don't have a bad headgasket.
If it's high crankcase pressure (blowby) and you're sure that it's not a clogged PCV (flametrap, non-turbo) related problem, then you're next best step is to have the engine tested by doing what's called a cylinder leak down test. That test helps diagnose problems like bad valves or possibly in your case (IF it's blowby, PCV system OK).....bad rings.
You need to know that before tearing into the engine as if it's bad rings and you have someone replace the headgasket only, it'll just be a waste of time and money because if it's rings, the cyl head will need to be removed yet again.
Make certain the problem is properly diagnosed. The only time I've once seen a FWD (white engine) with bad blowby, rings was with a car that had a bad t-stat for many months and the customer drove it that way (overheating) for many months. A clogged or non-functional PCV system will also cause blowby.