First off, This is a awesome project. =)
I've had experience with 3 of the 4 options you've mentioned above. Once my stock 3rd gear died on me I Ran the OS cross-mission in my GTR then eventually went to the OS88, and am running a PPG dog box in my S15.
I'd stay away from the OS cross-mission for your set-up. U need a dog mission or that auto.
If you want dog enguagement as u know the PPG is much nicer on the street. 88 is great for the track and under wot... Can't beat it IMO actually and the ratio options are a bit more friendly, espically w/ the big twins but, on the street not so much. Every stoplight, passin on the highway etc....clunk, clunk, clunk, down through each gear everytime. No skiping or quick jumps to N. You know what I mean. And your correct about the service being less expensive except on the intervals, and according to my records. I do overhauls once a year and from the looks of it could probably go quite a bit longer on the PPG after seeing how well things have been holding up.
Another thing that u hit on is fitment, w/ the GTR boxes.
FYI, Friend's racing in JP does their own custom version of a OS88 GTR box where they remove the transfer case and add a SR bell housing for their shop car's so they fit right in S-chassies. I'm sure they could do a version for u that keeps the RB bell housing.
Your car is going to be so hardcore anyway, Option 2-4 would all be fine. But after I read your post. The auto may be the way to go, given what your plans are for the car. Next I would say PPG, based on the fact u still want to street drive it and it's a bit less expensive. but the OS88 is pure sex..
ah tuff call.
Feel free to hit me up if you have any other Q's
suscribed =)
