You mention here to use a good quality latex primer here. It has been my expirence to use latex primer only when your bonding to another latex finish. Exception to this is in using an adhesion primer like "Grabber" or "SealCoat". Both are latex but have unusual adheive properties.
If a latex PVA primer were to be used over a alkyd finish with any amount of sheen, it can lead to some serious adhesion problems. I've had so many projects in the past where someone has done just this sort of thing, all have been a nightmare for adhesion.
I'm just being curious where your coming from. Am I missing someting?