Question about piston to wall clearance
 

Manley and VT both say .0035

Anyone disagree for some forged slugs ?

Forged pistons expand and contract more under changing temperatures, so they usually require greater piston-to-wall clearance than cast pistons. Also a nitrous or supercharged engine requires additional clearance also.

I would say .0035 -.0045 for NA Forged
and .0045 - .0055 for forged nitrous or supercharged.

Minimum and realistic maximum loose fit clearances.

bwhip fades back, fakes left, fakes right, shoots and a swoosh.

You piston manufacturer should include a spec sheet that comes with the slugs which has suggestions for clearances.

It did, it said .0035 also for a modular ford.