This differs from Bitcoin's current operations, which suggests that altering existing opcodes to exhibit new behavior may not be sensible. Instead, it might be preferable to only extend the acceptable input range for existing opcodes. The introduction of OP_MUL could require special handling of overflows, a scenario not well-addressed by the current interface.

Regarding data encoding, there is a discussion on whether inputs should always be 8 bytes long, favoring simplicity in design. Although little-endian encoding is prevalent within the protocol, the preference stated leans slightly towards little-endian while recognizing that having two different encodings would be problematic. The email also discusses the potential modification of CScriptNum, a construct that wraps around int64_t and includes serialization, deserialization, and arithmetic operations with overflow assertions. By modifying CScriptNum to support 64-bit integers and relaxing the input length from 4 to 8 bytes, existing functions and operators wouldn't need alteration.

The use of CScriptNum is consistent in other parts of the protocol such as OP_CHECKLOCKTIMEVERIFY, which allows up to 5-byte arguments. The conversation touches upon the lack of malleability concerns with 8 byte sizes being mandated. This leads to a discussion on integer values as script inputs and the potential shift towards a stricter encoding. The topic of literals like OP_1, OP_2, etc., comes up, highlighting possible complications with duplicating these opcodes for a 64-bit version. A suggested solution is to employ a conversion opcode after the literal or to avoid introducing separate encodings altogether, so the semantics of OP_n remain constant.

Finally, the email addresses the existing Bitcoin Virtual Machine (VM) and how it cannot be simply modeled by a state transition function due to factors such as the position of the last executed OP_CODESEPARATOR, the conditional stack for if/then/else branches, and the remaining checksig budget in tapscript. The idea of OP_ENABLE64BIT is criticized for potentially introducing a third VMInterpreterState, which could complicate consensus issues. However, the consensus seems to lean towards the concept that a separate leaf version would be a cleaner solution than an OP_ENABLE64BIT approach.