According to this post, you're missing a ground wire, but I don't see that wire in tacoma diagrams.
http://board.marlincrawler.com/index.php?topic=54868.0


Here's a tacoma diagram:
http://www.2rzturbo.net/wp-content/uploads/2014/12/1998_tacoma_Charging.pdf - which doesn't indicate a ground.
and another giving the same thing:
http://www.2rzturbo.net/wp-content/uploads/2014/12/2rz_alterator_wiring_diagram.jpg


On the 22R application, I found this, see the section on an wiring an internally regulated alternator.
http://www.offroadsolutions.com/tech-info/22r-fuel-injection-conversion-harness-85-88-donor/

Original IC Regulator Connector To Newer Alternator Wiring
-Smaller white wire To Smaller white wire
-Red wire To Red wire
-Yellow wire To Yellow wire
-Large white cable To Large white cable

There are indications on pirate of a franken-alternator using the 22R regulator and 3rz alternator...


Non-alternator questions:
As well as I can remember, the 22R has an oil light switch, not an oil pressure gauge, can you clarify?  On the 22RE, the 3rz oil pressure gauge sender and the 3rz gauge sender were not the same, but both were BSP thread, so I just swapped them.


Can you indicate what you did for the tach?  I know about the pull-up mod, but I'm curious as how you dealt with it.