Made it back to the range today with the 8mm Mazon . Shot @ 100 and 200 yds. Temps were around 20 deg F. Still shooting 195 gr Hornady bullets with IMR 4350. 68 grs of 4350 gave me groups in the 1 1/4 to 1 1/2 inch @ 200yds. Not sure what other bullets I will try next.

It has been kind of cold here lately so trips to the range are few and far between. (-32 C this morning). Tried the 175 Sierras with 4350. While they shot OK they don't really offer anything the 195 Hornady's provide. Think I will try something that will penetrate a little more. The 200 gr Barnes TSX should fill that bill.

I have nothing to add, other than to say this is quite inspiring. Thanks for sharing your project.

Another update on shooting the 8mm Mazon. Worked up to 70 grs of IMR 4350 with the 175 gr Sierra. They grouped around an inch @ 100 yds. Never had time to try them @ 200 yds. 70grs is not max with this bullet. Will re-try 70 and maybe 71 & 72 grs to see which groups best.
Also tried the 200 gr Barnes. Dropped back to 63 grs and worked up to 65grs. Pressures are still quite low. Groups are about 1 1/4 inch @ 100yds and POI was about 2 in lower than the 195 and 175 gr bullets previously tested. I was concerned I might get a bit of copper fouling in this old Husqvarna rifle. I was pleased to see there was no more fouling after shooting the Barnes bullets than there was with any other brand of bullet I have fired out of this rifle.
I have an 8x68 and a 8mm-338 .Case capacity and loads on my rifles are identical,as are chronographed velocities (+ /- 25fps with everything tested). Case capacity on the 8mm Mazon is slightly less (a couple grs) but I am seeing very similar loads developing. I suspect velocities will be similar. Will see in the spring when its warm enough to drag the chrony out.