exactly if you are on a standalone there is no reason to get anything smaller than 1000cc with the EV14 type of injector. see the chart above. EV1 I would stop in the 660-880 range. EV6 are less common but are the previous generation so they are pretty good but not as good as the EV14.
this will give you a good idea on the technology that went into each one.
EV1 was made in the 70's (this is what most use stock).
EV6 was made in the 90's (newer stock cars than ours use these).
EV14 was made in the 2000's (all new high performance cars use these now).
There are 2 reasons you can have such a large injector and have such a good idle with EV14.
1 is that the EV14 is completely different from the older injectors, instead of having holes on the bottom to try and get a better fuel spray, it has a ball and seat design, so when the fuel is sprayed out due to the ball and seat is sprays in a "Conical" stream which gives you excellent atomization, which is why you can spray so little fuel with 2000cc injectors and have it ignite near perfect every time.
Another improvement is the injector lag time or injector dead time. due to the new way of actuating the ball and seat, it takes only a fraction of the time to get the injector to spray, meaning the injector "dead time" values are very low, so that means the minimum amount of fuel that you can inject is much much lower. this allows a 2000cc injector to be able to inject only enough fuel for 650 rpm's, whereas if you had an EV1 injector it would overfuel cause its minumum open time or "dead time" is much more fuel than you need at that rpm, so you have to raise the idle and let more air in = crappy idle.
hope that makes sense. standalone = get some EV14 1000cc or if you need more fuel they go up to 2000cc.
on a standalone, EV1 or EV6, forget about it.
If you are using a factory toyota ecu, they generally use the EV1 type of injectors and maybe the EV6. I have not used a EV14 on the stock toyota ecu, they can probably work but the dead times are different so you would probably need a different CC, or maybe the computer can adjust if its a small amount.