Well, there are different booster mount patterns...but no, master cylinder mount patterns are the same. Generally speaking power brakes and manual brakes have a different bore size for the master cylinder. Swapping bore sizes will affect brake feel and travel, whether it goes from softer to harder or harder to softer will depend on which way you are talking about.
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Here is a good link that explains it way better than I can. Essentially when talking bore size(with all else being the same, stroke, brake cylinders or pistons)...a larger bore(that what you currently have) will create a stiffer pedal with a shorter travel while a smaller bore will create a softer pedal with a longer travel.