Camaro's in stock form are horrible to drive, especially with stock seats!
You can do all kinds of modifications without hurting the collectability of the car provided you store all the takeoff parts.
The Tremec close ratio 6-speed was the single modification that made me want to drive my car at every opportunity.
The critical contact point items to myself are the gear shift, steering wheel, and seats. Don't cut budget on those items as they give you direct feedback and input to the car. I went Tremec/Momo/Recaro and have never regretted the expense. The downside is you'll most likely have to alter the trans tunnel and I'm not sure how much collector impact that would have.
Good shocks like Ridetech's HQ's would be my first suspension mod. Then firmer spring ratios. Then geometry corrections to the front suspension. C5 front brakes are a major safety improvement and rear disc's step it up another notch. Then you'll need wheels to clear the 13" front brakes and you have a very enjoyable car to drive and you haven't hurt the collector value.
Those mods will make the car fast enough for street use with the stock engines IMO, if you want more consider the GM Performance Parts ZZ383 (450hp) or one of their LS platforms. For a desirable collector car I'd keep it simple with the 383 retrofit.
Detroit Speed, Global West, Ridetech, Speedtech and others all have quality components that will dramatically improve the driveability and ride quality.
One other item is the steering box, I had Lee Manufacturing rebuild my OEM box and convert it to 12.7:1 with their firmest valving and that was another major 'feel' item.
Hopefully that gives you some good food for thought.