From previous experience in breaking stuff from high powered track cars, my VX SS build was based around usable street power and reliability
The weakest link was the 4l60e transmission, Craigs rated their bells and whistles build to 600hp, so my build was limited to around 500hpatw, which gave me a 20% safety fudge factor, which is still about 600hp at the fly, which is about as much as I would be happy with for a LS1 with a stock bottom end
To get that we used the 85mm pulley, the biggest one that would fit on the 2300
My advice, until you get your T400, is to go a bigger pulley, yes it will drop your power, but it will give your built 4l60e some reliability
As for usable street power, I wouldn't want anymore power than what I have currently, I have enough trouble with traction now, whilst laying 11's is novel, it doesn't equate to fast
The only way I can get it to hook is some drag radials, which removes the whole streetability of the car
Whilst drag radials are good in the dry, if it's raining, it's like ice skating, and as I drive this thing everywhere, well I did before the lockdowns, I need tyres that are safe to drive in any weather
Keep us updated on your T400 build, sounds good, albeit bloody expensive