The IS 85 (or IS 1 or JS 1) I made after cutting off the guns from the Takara JS 2 model to convert some ISU 152s into ISU 122s (see my other post covering that). I replaced the gun with a brass rod which was straightforward but I then had to carve the front glacis of the JS 2 hull as the IS 85 has much less smooth front armour. I did this with a small file to get the vertical part and then used a craft knife to scrape the remainder to the right shape.
The KV 85 was more straightforward. I just cut the muzzle break from the gun of the Takara JS 2, sat it on the hull of a Takara KV 1 and repainted.
I know you can get at least the KV 85 from some metal manufacturers but I have so many Takara Russian tanks I was keen that they all match in terms of scale.