I have a turk made up of parts from an old gew 98. my concern is that the gew's were made from 1898 to 1935...do we know those were done right, in the mettalurgy department?

I have been told that by 1940 the process was pretty much known worldwide, but was heat treat in 1898 ok? how would I know before I try to sporterize this?

It's a little more complicated than at first it appears. When I wanted to barrel modern Mark X Mauser actions, the smith first Rockwell tested the bottom of the action flat at the front ring, before barreling. Most barrel makers that do rebarrels will test the action hardness first, Pac-Nor being an example.

When I had two old Siamese Mauser actions barreled, these made at the Tokyo Arsenal, Japan, I sent them out for hardness testing and heat treating if needed, but they came back with a report that no heat treating was needed. You may give these folks a try, IIRC they were the company I used.

http://www.industrialheattreat.com/index.html

Rockwell testing of old Mauser's isn't an exact science. they were surface hardened, not through hardened so a traditional Rockwell test will probably lie to you because the hardened layer is relatively thin, by design.

If it doesn't have lug setback, you are probably good to go. If you are going to dump big money into it, have it annealed and then re-treated after the mods are done.