How much lateral clearance do I need in rear? 335 on 18x12 in '72 Nova

[k72nova]

Question: is 1/2 of clearance on either side of a rear tire enough room for track racing?

Backstory: I may have made a mistake with some measuring and tire/wheel choices on my 72' Nova. I have 18"x12" rims, 13" overall width, with 335s. I'm running a SpeedTech torque arm and DSE mini tubs, I have approximately 1/2" of clearance from tire to control arm, and 1/2" of clearance between tire and quarter panel. I'm worried that it will not be enough for cornering at the track. I noticed that pretty much everyone running this rear suspension runs a 315 which made me start really thinking about the likelihood of these working, I looked at a lot of track cars over the weekend and they all have closer to 3/4"-1" of lateral clearance.

[USAZR1]

1/2" clearance would be my minimum clearance but as mentioned, 3/4" or more would be better. Have you actually driven your car yet, with that rolling stock?
Worst case scenario, you can switch to BFG Rival 315's.

[k72nova]

No I haven't driven it yet, I'm still mocking everything up, I'm toying with the idea of widening the quarters but I'm not sure I trust myself quite that much to make it work, and I worry about putting a 315 on a 12" wheel, recommended rim size maxes at 11.5, not to say it can't be done.