decided to go turbo

[Lord Warlock]

I know that in the 70s ACCEL made a turbocharger kit that used a manifold that sat under the carburetor like a spacer plate and the piping connected under the carb and down to the exhaust.  My cousin put one on a 68 Charger with a 383 and a 4spd, and it was downright nasty to ride in.  Definitely made an impression with me as I bought my charger about a year later.  I got to ride in it the summer of 77, got my charger the summer of 78.  

Wish I could offer advice to you, I have a twin turbo dodge stealth that I've done work on but nothing like fabricating my own system, I put on larger turbos, boost controllers and many modifications eventually getting close to 450hp to the wheels with a 3.0L v6.  Can't imagine what a dual turbo 440 would feel like.  The single turbo my cousin put together probably was capable of mid 11s, but he also built race cars and worked as a mechanic for years.

The trick to avoiding turbo lag is having enough power by the motor alone to launch strong up to 2500rpm, and then the turbos kick in like a 2 stage rocket.  It isn't that the newer turbos are more efficient or do not exhibit turbo lag anymore, its just that they starting matching the sizes of the turbos to the application where it was unnoticeable.  The larger the turbo you put in, the higher the rpm that it usually begins building boost, and the more likely that you'll get lag.  My turbos were absolutely dinky looking (13G's) but will hold boost to 26psi if I wanted to run it that high, I usually keep my boost set at approximately 14psi or 1 bar.  Boost for me begins at 2300rpm and is at full boost at 3400rpm-6000 where they start to lose some boost on the high end, but at that point you're going so fast you don't care.  Redline on the car is 7300.

[Rolling_Thunder]

small turbos = quick spool
big turbos = lag....   

So moral of the story is find something that spins up fast enough (calculate your torque convertor off of the turbo spool rpm) but is big enough to move air up to the rpm band you plan on operating in....   

The best thing would be EFI with your turbo with an external BOV - i've never ran a blow through turbo on a carbed system - tuned TT on a 1967 Chevelle for Rob Lake but that's about the extent of my brain cells...    I though about a TT set up on a 318 poly but ended up selling that car when I enlisted - never got around to the TT set up.

[Lostsheep]

I was originally going to do a single turbo on my 5.9 Magnum swap. Had the majority of the parts, and some of the motor internals set up for it, but life happened and I traded the main part "The Turbo" for some other goodies on my daily. But I'd be interested to see where you are on this project.