I really like the handi-rifle cocept now that they will retro fit barrels.
I believe you can use the same reciever for all the rifle calibers.
Shot gun recievers can not be refitted with rifle barrels.
I'd be leaning towards a 22 Hornet and then have it made into a K-Hornet as funds allowed.
This would be a great walking rifle and confidence builder for a young shooter.
At one time or another I've had:
22 Hornet
223
30-30
357Max
44
45-70
410
20ga.
A shrewd talking buddy got my 357 Max barrel/Leupold 2.5 in trade for a new (No Safety)Marlin 1894 in 357.
I thought I skunked him til I found out they made damn few in "The Max".
They made it again about 5 years ago BUT in a heavy (and to me useless) contour.
I've still got the old H&R Topper 12ga. 18" with a poly-choke. It fits in a back pack and lends a great deal of comfort...