valve spring retainers

I'd say yes as that's the recommended spring, 926, there are no notes regarding seat cutting. Installed height is 1.80 and pressures aren't insane high, 110ish. That's the easier solution using new. If the stock springs, when tested, have decent pressure on seat and over the nose, run them.

Here's another potential issue. Std chrysler multi-groove valves? I don't recall any +.050 valve locks for those.

IMO, the 911 are too heavy on the seat at anything shorter than 1.900. At 1.800 they are stupid heavy for that size camshaft.