Mostly have little appreciation of sentimental b. s. , as long as modification is done well enough that value stays the same, or increases. As long as mod improves looks, reliability, or accuracy. With about two trillion of 'em floating around, your MKII won't ever be any sort of "collectors item". Use it!
Or, that could be a good reason to buy an additional MKII, or even try on one of them new MKIII's for size.
Somebody makes a replacement grip panel with scope mount attached. Looks kinda Goldbergish.
Bob
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Much discussion of which 9mm will expand, and how much. But for sure a 45 WILL NOT SHRINK!