I'm only using NX-5700's, so never needed to try.
However, I've heard from several that they were successful in making a 5300 work down in the 70cm band, as far down as 440MHz.
But, keep in mind if you want to use analog, the stock NX-5300 and KPG-DN1 will force you t use 12.5KHz narrow band FM. You would need to procure a W-license from Kenwood to open up the wide band FM.