Interesting, although I fail to see the problem. Is this your only means of transportation? A high HP 7M is not a very wise choice for a daily driver. Atleast I assume it's high HP, all I've seen is "very fast" and OS Giken.
I can see a few issues, the GE vs GTE tach have different values, so I can only assume that a GTE digital dash would not read the GE signal. If it's just for temporary while you rebuild the original 7MGTE I don't see a problem with leaving it unhooked and driving by feel/sound. The speed sensor should bolt right on the trans no problem and the other sensors are the same. For the ease of temporary installation why not leave the R154 in. Just replace the clutch packs and discs, it costs less than $600 (US) for both OS Giken rebuild kits, which you would have to replace regardless and break in. Plus no need for any wiring or finding an auto driveshaft and all other automatic swap parts. TEMS is a seperate system and ABS should not be affected by the change.
Another option would be to use the GTE wiring and electronics on the GE engine block, just return the electronics back to stock and swap the distributor out for the CPS, coil packs, AFM, injectors, and all the other sensors and electronics. Run it like that until you rebuild the engine, then the swap back is simple.
If you want to do a 1UZ or any other engine besides a Toyota I6, don't expect any help from me.
