Does anyone know for sure if 383 pistons will work in a 426 wedge motor..Thanks, Alex

You would have to verify piston to wall clearance and balance but, they "should" fit. Why would you want to, as the compression would be so low?

No, definitely NOT
I've built many of both of those motor over the years, the 383 pistons have a different compression height than the 426W pistons have, both the race wedges and the street wedges won't work unless you went to a custom made rod and or a stroker crank and rods to make the 383 pistons work and visa versa
Don't forget about the block deck heights, the rod lengths and all the other little things being different between those two motors.
I'm in the middle of finish building a 383 stroker motors for my1969 Dart GTS 383 4 speed car, it has a 4.280 bore with a factory 440 stick shift crank in it that has been offset ground to have 3.91 stroke with 383 main bearing sizes with BB Chevy rod journal sizes (2.200) along with a set of after market H beam steel rods with the BB Chevy wrist pin size and set of custom forged pistons. It will have 450.03 C.I. and have around 9.5 to 9.75 to 1 comp ratio for today pump fuel
I have put a stock 426 street wedge piston next to a stock 383 335 HP piston, not even close to looking the same on the wrist pin location

Thanks for that important info! That was my last hope for this block

Pistons for a 426 wedge should be available ?

You can have any of the custom piston makers make them any way you want them

no can find anywhere. Nowonder I can't sell this 426 wedge block. Was only asking 300 for it.