I have a blued MK II Target, with the somewhat scarce 5 1/4" barrel. My Blue Book has a separate listing for this model for the MK I, but not for the MK II. Would Values be close to the same?
No. The 5-1/4" barreled Mark I is a rarity of sorts, and generally brings about double what the 6-7/8" Mark I brings.
The Mark II 5-1/4" on the other hand is scarce (they were only made a few years), but the MK514, KMK514 and KP514 just don't have the following of the 1952 to 1955 production 5-1/4" Mark I's.
A slight premium on the Mark II, yes if NIB, but no extravagent premiums.
Chet15