I've used a Jacobs Notrous Mastermind on my SBC motor that safely runs 175bhp of Nitrous.
I know the old chevy isn't the same as the 1UZ, however the fitting instructions included full details of how to fit to a modern ECU'd injected engine.
Please look into this unit as it is great. As well being able to run normal timing and then retard when the Nitrous flows, it has many fail safes such as low fuel pressure cut offs, Nitous pressure cut offs, rev limiter for the gas, then another engine revlimiter 50 revs after (prevents engine blow ups). The engine rev liiter also contimues to work when the Nitrous is off.
In addition you can set what revs you want the gas to flow, what %age of total flow you want at that point, max flow revs, and it will increase the flow in proportion between these 2 points.
If you are playing with Nitrous then a unit like this is a must.
Cheers
Mark