1972 Demon with 71 340 casting

No. The 68-71 (and some early 72) had a small dome on the piston that achieved positive deck height and gave the higher compression. The later 72 and all for 73 engines had 4 eyebrow flat tops.
My 340 was built using these pistons.
Sealed Power 428P30 Sealed Power Cast Pistons | Summit Racing
I guess it's safe to assume it doesn't have the stock 10.5:1 compression form the factory anymore.