I street drove a 200 with a .60/.63 SVO mustang turbo for a few months. spooled plenty quick on a bone stock 200. Blew through a 350cfm holley. Ditch the mech pump and go with an electric wit a boost referenced regulator.
IF I were building a US motor again I would prob go with my build as it were before I parted it out for the XFLOW250 build...
1. Similar header design but instead of square tube I would just build the whole thing from some flat sheet (14-12ga with a beefy flange) and have it waterjet/lazer/plasma'd out (I do own a plasma now) to give it some bigger runners and log and then just bend it up on a brake to angle it from the. one could lay this out pretty easy with some cardboard mockups. Put a wastegate flange on it for an external gate.
2. I would stay flanged for a T3 frame turbo. The turbine on these (with a stage III wheel/housing) can support 300-400 with ease and there are ALOT of turbos you can swap on easily.
3. air/water intercooler. Plenty of room under the hood on a manual steering manual brake car with no AC.
4. Megasquirt with a MAP sensor, coolant temp, air temp, and one of my TFI distributors (I did a write up about 6 years ago on this) and maybe a TPS sensor. This will let you dial in a start retard, run a high idle solenoid, boost retard,fan control, fuel pump control, rev limiter and be a stepping stone for a full EFI setup.
5. a NEW carb. same choke mods and all. maybe a fancy metering block and anular boosters.
6. Better BOV. not that I had issues but didn't trust a $40 ebay chinese one.
7. Custom ground cam for a turbo (I was building a motor to run a mild comp 252h? I think it was)
8. Decent bonnet. I had scored one for pretty cheap (was in school at the time)
now in an all out build I would get one of Mikes new heads and EFI that. Instead I just bought a couple Aussie XFLOW motors (back when the dollar was worth something)
on my XFLOW 250 I am starting out with a .50 trim TO4E wheel and a stage II turbine in a .63 housing I think it is. Will spool fast but will work for a starting point in dialing in the car and EFI before I step up and really blow on it.