The stock Windsor pistons have a good sized dish in the tops, nothing to worry about as far as piston to valve clearance. Do check the torque values though. I bought a short block done by City Motor Supply in Dallas locally from a Napa store about 15 years ago and the rod bolts were torqued to double the correct value (50 ft/lbs vs 25 ft/lbs for a stock 5.0 rod) I replaced those bolts with ARP's and it held up fine afterwards even buzzing it to 7 grand with he heads cam and intake I bolted on it.

 

What I would so first, of you don't need this as a daily driver, is pull the heads and check post on deck clearance.
That is, how far down the piston is in the bore.
You may not have had any issues so far in stock form, but upping the compression, and a new cam may bring some to the surface.
Typically, you want the piston .040" to .044" from the head after the head gasket is installed. So if the piston is say .020" down the hole, you will want to use a .020" to .024" head gasket.
This helps fight off detonation even at moderately high compression ratios, I've personally gotten by with 11:1 on pump gas on engines before.

The reason I bring this up, is I picked up a reman engine and was putting new heads on it and thinking about a new cam.
Come to find out, they used the cheapest parts to redo this 351w. The pistons are .047 in the hole to start, so even with the thinnest gasket I can get I'm still .020 deeper than ideal.
But, that's the name of the game, they are out to build and resell as many engines as they can, as cheap as they can.