friend of mine just gave me a 60mm throttle body from an 87 gt. will this do anything for me on my totally stock 86 gt? if it will, would it be a direct bolt on?
Direct bolt on. Won't do anything by itself. Maybe 1HP if that? The '86 upper is designed more for low-end to mid-range. So, just having having a better flowing TB by 2mm isn't going to be worth any hassle.
If you want a few more HP in the upper-end (~3K+) at the cost of a few HP in the low-end, then change the '86 upper to an 87-93 upper along with the 87-93 TB. Direct bolt on. In reality, there are trade-offs in design and choices.
IMHO, I agree that the 5.0s have so much low-end grunt, that changing the '86 upper and TB to the 87-93 upper and TB is fine. IMHO, anyone that claims that they can feel that few HP difference has their head up their finely calibrated butt-o-meter.