If you're going twins, I would run a pair of precision PT61's .81 or .96 A/R tang housings, if you're going single I would run
NO SMALLER than a "small frame" PT88. A single T4 housing, even something like a T76-GTS would be severly restrictive on something like a 408 which flows a ton of air. If you don't care about PS or AC i'd do a mid-frame PT88 (uses a TV housing and flange, the small frame uses a T4 flange but a much larger housing and wheel than a standard T4 turbo) with a full 5" downpipe, it would make some decent power
Also, FWIW, for a turbo setup i'd go smaller than 408 inches if you want a street car. Any 302-347" motor with a PT76-GTS will be making full boost not long after 3000 RPM's, you could easily squeeze 700+ to the ground out of it on pumpgas (look at brent, 770 to the wheels spinning it to 5000 with 18 pounds of boost on a 302" engine!) but the turbo will push enough air for 900+ on race gas. Using the 8.2 deck 302 just makes it easier to get it in there, easier to buy parts for it, etc.