A 50 profile is the correct size to keep your overall OEM diameter, which is what keeps your speedo/odo accurate. But a 45 won't throw it off too much. You can see how much by playing around with a tire calculator.
Btw the tires are Toyo T1R's, which are performance tires with a strong sidewall, thus they ride and handle like a 40 or 45 does. Anyway, good luck with the tire search.
Thank you, that is the look I was going for. I also have another car that is all blacked out so I figured two opposite ends of the spectrum was a neat idea.