An odd throttle body question

[Turbo F-bird]

Anyone know if a throttle body from a non-turbo 3.8 SFI (around the 87,88,89 area) or 3800 is pretty similar to a GN one but slightly smaller bore? I have a GN TB on my Turbo Sunbird and would like to go a little smaller because I think the GN one is a tad too large and is hurting my bottom end and mileage. I'd like to find one around 50 mm that swaps right on so I don't have to alter a bunch of stuff and find out there's no benefit. Anyone know if an old Park Ave TB is smaller bore and a close fit?

 

[pacecarta]

same size , aside from extra casting for the throttle shaft seals on the turbo they are identical

 

[Turbo F-bird]

That's a bummer but I appreciate the info, thanks! I'll keep hunting.