Uhh… what?
First, the "conversion" of kg to J should be something you don't have to memorize, since you should know that the speed of light is 3E8 m/s and that E = mc^2. Is it really that hard to square c?
amu --> MeV … no, don't memorize it.
seriously, focus on actually being able to understand the concepts and solve problems. You shouldn't be digging this deep to find stuff to memorize.
one thing which would be good to memorize when it comes to "conversions" is how to break down every derived SI unit into more basic SI units, and the equivalence of different SI units in general
for example,
volt = watt/amp = joule/(amp*s) = (N*m)/(A*s) = (N*m)/C = J/C
knowing things like that can make solving complex problems by dimensional analysis very very simple.
