No, actually, no one can tell you that. Reason being, neither a "Blender Unit" nor a "SM64 Unit" are really defined. You need an actual, physical quantity in order to relate measurements.
A real-world
estimate of an SM64 Unit
could be made by taking careful pixel measurements, working under one (and
only one) of the following assumptions: That Mario is the
height of an average human; That Mario is the
width of an average human; That Mario's jump height is equivalent to that of an average human.
In order to use that last one, you
also need to assume that physics work the same way in the Mario universe as in the real one.
Alternatively, you could work under the assumption that Mario
walks or runs at the same speed as an average human, and note that Mario runs at approximately 22
units per frame, which equals 660 units
per second.
Note that all these require
assumptions, which may or may not (most likely "not") be accurate.
~!{0}!~
And all that difficulty is just on the SM64 side of the problem! The Blender side is, fortunately, easier. As I mentioned, a Blender Unit has no world-defined size. You can configure Blender to treat 1 BU as equal 1 meter, or 1 centimeter, or 1 Foot, or 1 Inch, or 1... literally any other unit of distance. Just "A Blender Unit", however, is meaningless.
Now, I
do realize you have been inactive for over half a year, but I hope maybe you'll come back and see this, or else it will prove helpful to someone else. We'll just have to wait and see, I suppose.
A word fitly spoken is like apples of gold in pictures of silver.
--Proverbs 25:11