Looks like a fun project...I have the schematic here for the internal circuit (this build utilizes 2 of these circuit boards), maybe someone can create a nice compact vero layout that will accommodate the aluminum mic housing...anyway, here it is!
EDIT: There is also a more simple condenser microphone build (from the same guy) that uses the same circuit (only 1 board as opposed to 2 as mentioned above) here:
I love that you’re into this and I wouldn’t want to poo poo your idea but with such high input impedance the layout is critical for noise performance. I wouldn’t choose stripboard. As much as I hate perf sometimes it would allow for a better layout with this type of project.
Check out the 1G resistor from gate to ground. That’s one gigaohm and it sets the input impedance. Before building some mics I didn’t even know 1G resistors were made.
The wire from capsule to board should be as short as possible and connections at that point of the circuit would commonly be made on insulated turrets. I can provide mouser part #s for those insulated turrets if needed. You can see this guy built that part of the circuit floating