If you don't tow and can stand the lag, a S475 can be streetable. In terms of a fun turbo for stock injectors, the most fun stock motor LB7 I've been in ran a 66mm Silver Bullet. Industrial Injection gets a lot of hate, but I've actually had good luck with them, including two turbos and a set of +60% injectors.
You do need sane tuning to keep rods alive with a smaller turbo.
As for how fast the silver bullet will light, I threw a bigger tune on my brother's truck, and a WOT snap in 2nd blew the tires off and it RPM'd so fast is spun the stock balancer on the crank.
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