Your still "missing the point" here.
Steel seats are good for commercial engines especially with the catalic converter. NO WAY was 300,000 miles put on a passenger car.
Most Hot Rods use them too.
But for a stock 250" engine, for use in a passenger car (W/O a 'CAT') save your money as you'll never get it back.
My original 327" Bell Air has 138,000 & never been apart and been using unleaded since it came out(60.000). Last tune up the compresson was close to perfect.
It's the usage or 'planned usage' that's the main factor.
