Just don't use APC14x8 on that Saito 72. It is the largest prop you can use on Saito 72, but I don't think it will handle well without 30% nitro. Also, there isn't enough ground clearance with stock gear on Oxalys 50.
Either planes will do ok with Saito 72.
Both were designed around YS63. Oxalys 50 was for YS63, Osmose was for YS63S.

Add additional support for LG block. Check for fuselage straightness before start building.
I've been waiting for a replacement fuselage for Osmose since May. No luck.