Horsepower Estimate?

Anyone want to give me a horsepower estimate? This is all I know about the 340.
1973 block
Bored 30 over
J Heads (probably not ported)
New pistons and rods (no idea what they are)
New lifters (?)
8.5:1 compression (could be higher...not sure about head gasket thickness)
474/280 purple cam
RPM Air Gap intake
Holley 650
Hooker Headers




So many unanswered questions and a way to small of a carb in my eyes. We don’t even know if the heads were given a valve job and a valve job on a set of stock heads can make or break the guessing game. I had a set of “stocker heads” on my bench and I know how they did what they did. I just don’t know the particulars of what they did.