Sorry thats is an artistic photo and not a decent top down shot but this is the engine bay of a member here @VolvoHordz who has built a turbo 16v motor. I believe his goals are 500whp. It hasnt yet done any tuning so there arent any numbers to report on. A daily driven 600 - 700 redblock is going to be a pretty unruly thing. I would love to see one and definitely encourage you to have a go at it, but in my time with these engines ~300hp is the sweet spot to keep them reliable and livable with an 8v. A 16v allows you to spool a bigger turbo faster due to the increased volume the engine can now move so may smooth out some of the peakiness of a big turbo redblock.
I personally have never built a big power redblock and have only built motors that use stock parts. An old legendary car that used to be around was YLD244 which had a big garret on a stock bottom end. It didnt ever get dynoed but it would have made approximately 280 - 320 whp. The owner drove it everyday in city traffic to work.
You may also be able to look at the recipes from some of the European builders such as those from Bamse's Turbo underpants or Overboostracing who build big power 8v motors. Big power redblocks are a bit of a challenge here due to the steering shaft being on the right and interfering with the turbo plumbing.
It can most definitely be done, i think it may be a bit of a difficult thing to drive due to the size of the turbo you will need which will push the power up quite high as the spool will be delayed. It will be interesting to see what you come up with though. The base car looks fantastic.
Oh and welcome!
Overboost: https://www.youtube.com/@Overboostracing
Bamse: https://www.youtube.com/@eetziproductions
