6.1 Valve spring failure

The stock valve seal is a combined seal and seat.

The cage sits on this seal/ seat

The factory seal/seat and the cage combine to create the correct install height FOR THE FACTORY SPRING.

If you use the PSI spring, you can use the cage but I cant help you with advice on the correct shim, or seal.

You are FAR better off using the correct height aftermarket shim, locater and seal.

The locater removes any need to use the cages.