.17 Remington has the same case head diameter as .223. Case length is 36 thou longer though. The .17 has 2.150" OAL(SAAMI says 2.150".) vs 2.260" Max for the .223. There might be an mag length issue. Easily fixed though. Too short is easier to fix than too long. So you're only issue would be finding a barrel and that's not a serious issue because M700 barrels will fit. And M700 barrels aren't hard to find. Epp's wants $150 plus the cost of the barrel. You can have any .223 based chambering.
The .17 Remington Fireball isn't the same as a .17 Remington. The Fireball case is 1.410" long vs the 1.796" of the other Remington .17 cal.
"...17 calibres that are more available..." There really aren't any that aren't reloader's cartridges. Even Stateside the .17's are kind of unusual. Both Midway and Graf's(big time U.S. on-line retailers) show no .17 Rem brass available. Graf's doesn't list the .17 Fireball at all.