I have read some about the AK magazine conversions and know its a no turning back ordeal.  If it was done and done well do you think it would hurt the value of a Cherrys Import Yugo 59/66?  I doubt I would ever sell it but wondered how bad or good it would turn out money wise if I ever did have to.  I like the rifle and for me the AK magazines make more sense but on the same note hate to "ruin" the rifles value.    

I've never heard of a conversion to AK mags working properly on an SKS, though the SKS-D models which came factory-made using AK detachable mags are reportedly just fine.

Unless you can have a metal working "artiste" get you to SKS-D factory levels of reliability and sophistication on the conversion, I think you'll kill the C&R status, chop off 1/3 or more of the value of the cherry rifle and wind up with a rifle with feeding issues for your trouble.