That BBK Manifold does not look like it'd be very good for boost just to let you know... There'd be alot of un-even air distribution in that plenum for sure.
All TPI stuff is super expensive for little result. Boosted it'd be better.
Turbo Buick stuff is a excellent choice for a daily driver. It's got the best of both worlds there.... Power and economy. There's alot of new engine designs that are just now able to accomplish what the Buick has since 87.
A single turbo LS1 would be awsome....
Up to you with budjet and experience.
Here's what my 86 Camaro Hybrid turned out.
I drive it daily in the summer. With the changes I'm making this winter it should run mid 10's on 93oct. (this year went 11.19@123mph.)

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86 Buick powered Camaro...10.32@133mph
93oct Pump gas, through the mufflers on a Drag Radial tire RJC 5inch downpipe,.76mm turbo FAST EFI TH400w/brake
9"rear with 3:50's. Champion heads/new design intake.

86 Midnight Blue T-Type Final assembly underway.
89 Maxima with TA49turbo 13.4@107mph
with 244,000miles on stock engine.
92GMC Typhoon.. Wife's daily driver
Was 13.10@100.87mph 4bolt splayed built block. .61mm turbo FMIC. Going orange soon.