Pistons for Larger Valves?

[MustangChile]

I have a 1969 Mustang with a basically stock 302 CID engine.
I want to upgrade my valve train. Part of the upgrade includes the head.
In a few Ford V8 performance books(How to build Max Performance FORD V-8 on budget by George Reid and Mustang mustang 5.0 liter Performance Handbook by Peter C Sessler) Recomend using using 351W heads and using larger Chevrolet 1.94"/1.60" valves. I plan to follow this advice. That is, change my stock 302 heads, install the 351W heads with the larger valves, ported polished with other necessary modifactions, etc...

Now for the rest of the equation I will install screw in studs for roller rockers with 1.6 ratio, and will be running a cam with a max lift of .471". My pistons at the moment are stock however I will eventually change the to forged, but not for the meantime.

The QUESTION is: Will I have any clearance problems with the valves with my current stock pistons, taking into account increased valve lift and valve diameter?

When I will eventually change pistons to forged, what pistons are recomendable for the new head components

I have more information on my car at the following website>:
www.kovacic.tie.cl/mustang69
In the "model" link on the top bar are my VIN plate details.
The "modifaction" link also has other details as to what I have and what I wish to do.

All help and advice is very welcome and appreciated.