Which is better, OBDI or OBDII for gas->diesel conversion?

I'm (re)building a 6.5TD for my 93 Suburban to replace the 454 which has put in 390k pretty reliable miles, but is pretty hard on the wallet now. The donor truck was 94 so I have that wiring harness already with a new chip for the 5521 pump I've got to put in (to replace the old 5068). On a whim, I ended up getting a complete 1996 harness along with the steering column and instrument cluster so I could switch to the new style dash, but I'd still need to cobble together the rest of the dash bits. Since I already have all of the diesel specific pieces, this shouldn't be too hard.

Since my goal is ultimately as high milage as I can get (I'm using single dot pre-cups), I'm assuming that the later the computer, the better. Also, it seems that the OBDII system in the 96 monitors a lot more parameters for easier problem diagnosis. The only unknown yet to resolve is whether or not I can get my 93 vintage ABS module (which needs replacing anyway) to talk to the 96 computer since I don't think there was previously any communication between the ABS and PCM in 93 save the dash light.

Are there any significant advantages/disadvantages of the 96 over the 94? I'm not planning on adding any performance programming, unless it's documented to provide higher milage. I'd just like to be sure to take advantage of any improvements that GM made in those 2 years. Sorry for the length, and thanks in advance for any insight.

I would stay with the mechanical 1993 and OBDI myself. Avoid having the IP issues with the 94-up. If your trans is a 4L80E from a 1993 you could have problems with the OBDII not being compatible. In 94 they changed the force motor and maybe solinoid in the valve body. You can still use the 96 dash, but im sure some electrical connections will have to be compensated for.