DIY plug-in diesel-electric hybrid F250

[jray3]

I'm penciling on a diesel-electric retrofit for my 1987 F250.
Goals: Fun, increased torque and acceleration, ability to get max mpg, and bragging rights.
Qualifications: already built my own hi-po electric car.
Basic project specs: 6.9 IDI, 2wd with a t-19 4x4 tranny with the 6.32 granny and 1.00 fourth gear, 3,55 rear end.
Hybridization by adding a 6.7" dc electric motor of up to 156 volts through either the PTO or the transfer case. Both options would allow for electric-only drive, and also to disconnect the electric motor for long highway trips. PTO drive would allow me to continue the project by adding 4wd. However, transfer-case drive allows multiple gear ranges, is probably capable of more torque than the PTO, and has some ability to engage and shift on the fly, while the PTO must be engaged only at a dead stop. Anybody know of a downside to letting the PTO be driven, rather than be the driver, and maximum pto torque and rpm possibilities?
I can put in a lot of electric power; am considering setups of 25 to 120 peak hp, all possible using the same motor, which would only put out about 20 hp continuous, though the motor would rarely be used for more than a minute or two at a time... Max torque output of about 60 lbs.
Any comments or suggestions are welcome.