Tire and wheel help, new direction

[J.Shoot]

Ok, after taking the car to the track and not being able to hook up at all, we have decided to get a different set of wheels for the back of the car. I want to run MT ET street tires. What size wheel can I put on my Boss and get the tallest sidewall?
Can I go smaller than a 17" wheel? There's not but a couple of options with a 17.
Would it be better to go 18" wheel and will a 295-45-18 fit?
Or would the 305-35-18 be better, I would lose an 1" of surface contact but I'm wondering if the sidewall flex would help make up the difference?
Looking for suggestions from experienced drag racers.

By the way P zeros stink.

For those who aren't familiar with my car it's a 2013 boss that's been modded by TS and making over 600 rwhp, so I really need some tires that will bite.....

Thanks,
J.Shoot