Your thought experiment involving computation invokes some philosophical topics. In such a philosophical problem, the point is not to answer the question. But to take stock of the questions it raises. This type of meaning is known as inquisitive semantics to some. Your question certainly raises at least 3 thorny philosophical considerations. For instance, you may be committing a category mistake by placing CMOS devices in the same categories as brains isolated or embodied in consideration.
Brains Are More than Turing Machines
(Consider the PhilSE question Why do some physicalists use the Turing Machine as a model of the brain?. Also Consciousness in Simulation theory & AI, why do some believe that it is even possible?.)
For instance, when you talk about reverse engineering a MOS 6502 and reverse engineering the human brain, you are in a different complexity class. For instance, computer hardware is amenable to description by formal semantics. Consider the use of VHDL. From WP:
The VHSIC Hardware Description Language (VHDL) is a hardware description language (HDL) that can model the behavior and structure of digital systems at multiple levels of abstraction, ranging from the system level down to that of logic gates, for design entry, documentation, and verification purposes. Since 1987, VHDL has been standardized by the Institute of Electrical and Electronics Engineers (IEEE) as IEEE Std 1076;
Can the same claim be made about the human brain? While I'm aware of no canonical disproof, notions of cognitive architecture and embodied intelligence (SEP) are very complex indeed.
Analog vs. Digital
(Consider PhilSE question Is it there any specific and well known continous/analog alternative to Wheeler's discrete "It from Bit"?. Also Digital Minds and their perception.)
In systems that perform physical computation (SEP), it is clear that modeling Guernica with pixels is not a faithful reproduction. Pixels are mental objects, something many would consider abstract objects (SEP). But pixels are an approximation of the physical objects they represent. Consider the difference between a picture of a tin of cookies and the actual tin of cookies. Reproducing the picture is an easy problem for computation. Photographic copiers replicate pictures within a specification, for instance, differences being contained to not capable of being detected by the naked eye. But replicating a tin of cookies? The brain is capable where the copy machine is not.
Non-Determinism and Underdetermination
(Consider the PhilSE question Is there a term for materialistic non-determinism?.)
Part of your question asks about recreating a physical object. The ability to recreate a physical object would be a deterministic process. Notice how standards suddenly come into play. Say you accept a standard for physically replicating Guernica. Forgers are quite good at recreating faux art. But does that mean that if one forger can fool art experts that the forger suddenly has insight into what Pablo Picasso thought about his breakfast preferences? Human brains may be able to mimic other brains, but that mimicry doesn't confer ALL properties of the brain it is mimicking. Clearly, just enough to replicate one very specific skill at most.
In this way, the universe is non-deterministic. Unlike a math proof that allows you to move back and forth between steps with impunity, physical machines and their states are in some sense, lossy. Thermodynamics, for instance, means that the energy of the system inevitably is noisy. Systems of physical computation are not identical to the abstractions we create from them. Computer software has bugs, computer hardware has failures, the human mind forgets, etc.
Conclusion
Your Gedankspiel raises some fundamental questions. You ask:
Can Consciousness be Computationally Reconstructed from a Painting?
Probably not any more than photocopying a book allows you to rebuild the author from scratch. However, it raises some excellent questions about determinism, analog and digital reproduction, and physical computation. Clearly reverse engineering a microchip is not the same as rebuilding (if it's even possible) a consciousness mind. They are very distinct classes of ontological commitment.