I had created a thread documenting my progress on the MK-219 mods. If you searched for them on here, you probably already read what I had to say about it.
I took a cheater path, of a sort, since I bought the mod kit from Bill Sitler. It works very well and I have done the same mod to three MK-219 mics now. I am very pleased with the results. I find the microphones are very useful tools for the studio. At some point I plan to buy a fourth and mod it so I have a full set... of four! I just happened to have a case and foam that perfectly fits four MK-219 microphones, so on my C or D list of purchases, a fourth MK-219 to fill the empty slot in my case burns for my future attention.
Anyway, if you want a quick path to some wonderful MK-219 results, check out the Bill Sitler mod kit: Oktava MK-219 Modification Kits and Service
I know if you sourced parts out, you could in theory do this for less $$$, but then what parts would you buy? And you would buy 100 resistors when you need one, or ten caps when you only needed one and so on. So in that regard, the kit does offer some value. Also it could provide a person a starting point to maybe try swapping out some values for various caps for changing the sound if one were so inclined.
I did NOT really get into trying to bias the FET. Should I? I do not know. All three of my kit mods sound the same to my ears, and they sound good. Hmmm, maybe they could sound better, but I am not missing it.
In case you have an interest in checking out the thread I posted on the 219 mods I did, check it out: Oktava MK219 stock versus mod head basket versus mod electronics
On my post, I did not put up any photos. I started out taking pictures, but ultimately decided they did not reveal as much as I hoped they would compared with the text. I say that as a person who makes his living as a photographer, by the way.
Anyhow, I could not recommend the mods more. This is a worthy effort with fantastic results.