Importance of unsprung weight/is this handling suicide?

[formula]

Alright guys, I'm sick and tired of these friggin 15x7's and 225/75 tires--They're holding this whole "driving rapidly" thing back way too much. I'm also getting ready to do my brakes, and will need larger wheels in order to get rolling again. So-- I was goofing around on summit, and found cragar soft 8's for 70 bucks a wheel in 17x9 with 5" bs. This is close to exactly what I need to fit my car, so I'm contemplating picking up a set and then getting some nt555R2's to play with until I can afford year one snowflakes and bfg kdw2's. The reason i'd go with the 555's on the steelies is that, presuming fitment worked out alright, I'd hold onto those wheels and tires for track days. The only real problem I can find with the plan is that the cragars weigh 30+ pounds. each. Is this going to be a deal-breaker? I know unsprung weight is bad and should be minimized wherever possible, but how much of a difference would it really make for a weekend track car?