A straight fit would be unlikely. The Impala limbs, with a tweak, would probably allow you to shoot the bow again. Some of the beginners bows, have limbs that would fit and would need a peg fitting into them in the right place. I'm guessing that perhaps the beginners limbs might be a step down from the KG1 that might not sit well in the sentimental aspect. Keith Gascoine, with his connection to Marksman seems like the way to go. But not bespoke limbs; Impala limbs with a tweak. I guess he makes those limbs, with no fittings during the laminating stage. Last job would be to add the fittings; a barrel for the limb bolt and a peg for alignment. That part could be bespoke for your KG1.
I met him twice, once at Marksman where he sold me my Portland 2000. And once at his own workshop where he arranged to send me an all carbon riser compound. I had to return the bow, but what impressed me was that he did not charge me anything for posting the bow down to me, and without asking, he refunded all of the price of the bow.
He might not have time to modify the Impala limbs, but he might sell you a pair in their unfinished state.