Cut the check valve? WTF? the check valves are all that keeps oil from getting into the engine via those tubes. Replace the breather valves and run them to atmo for a while, (capping off the other ends, obviously) until the smoke clears. This is a great way to blow an engine, as excessive oil in the engine kills fuel octane and makes a great environment for preignition in the combustion chamber.
2014 Premium GT, SGM, Brembo, Auto, Tech, Comfort, etc. GT500s, Steeda UCA, VMP auto N/A tune. 100 shot nitrous on BBR tune. Best e/t 11.42 at 120.64
2012 Premium GT, Candy Red, Brembo package, 3.73, MT82, Comfort, Tech, et al. Procal tune, Roush UCA, UMI poly LCA, GT500s, Steeda red bracket, Hoosier 28x10x16 bias drags. Best e/t 11.91 at 115.23 RIP