[amsat-bb] Help with Mirage KP-2 mast mounted preamp

I need to replace the FETs for both: KP-2/2m and KP-2/70cm, I look for schematics and parts list for these units for some years already and wasn't able to find anywhere on the Internet. The "mysterious" FET seems to be the same for KP-2/2m and KP-2/70cm on the circuit (KP-2 rev. B) and it feeds another FET: J310 for 144Mhz and a J309 for 435MHz. I have couple spares of MFG1302 and 3SK74, not sure if it would make a good direct replacement ? Thanks  73 Ed PY2RN