I'd be glad to give you all the help I can. Thirdgens are my passion. It appears the lights I linked above will work. Like i said the companies can confirm if you call them.
Some info on the berlinetta: In 84, the berlinetta received a futuristic instrument panel that featured a digital readout for speed, an electronic bar tachometer with vertical readout, and movable control pods flanking the instrument displays. The berlinetta radio location in swivel pod mounted to the console forward of the shifter. There were two styles, both unique to the berlinetta. All a huge giveaway to whether you have a berli or not.
Lets double check and see what the car left the factory as.
5th character of you VIN: P=sport coupe or Z28 coupe, S=Berlinetta
8th character is engine but i'm sure if it has a 2.8 (VIN=1) in it that is factory.
10th character is year: G=86
11th character is plant it was built in: N=norwood, L=Van Nuys
Interesting fact about the thirdgens is that the V6 are balanced front/rear. Put some good suspension under it, some 16x8 wheels with 245/50r16 tires or these
http://www.ctw-motorsports.com/products/ with some 275/40r17's and you will have a killer autoX car.
Back to topic, If you have a berlinetta, you will MUST add a wonder bar to the front, I recommend this one.
http://www.top-downsolutions.com/ch...and-suspension/steering-brace-(aka-wonderbar)-for-1982-92-camaro-or-firebird-(a It mounts under the front sway bar bushings and strengthens the frame rails where the steering gearbox has been known to crack the frame. It would be a good idea to check behind the steering gearbox to make sure now damage has already been done. The wonder bar was a factory option in the IROCs.
Here is a link that discusses the triangular braces the tie the K-member and frame rails together. Second link also has great info. the braces i'm talking about are pictured in post 22. Make sure you have them too. Please read these two links.
http://www.thirdgen.org/forums/suspension-chassis/553927-front-end-bracing.html
http://www.thirdgen.org/forums/suspension-chassis/237871-might-cure-your-front.html
No, the 3 holes are nothing special. Maybe the help bring in more air for the radiator or a cooler intake charge but nothing to get excited about. The berlinetta was a fancy, luxury model. Never intended as a performance model. The berlinetta was usually advertised with a woman driver. check it out.
https://www.youtube.com/watch?v=YngjiFBX0Rk