Not best, but optimum Transmission?

The original flexplates will last 40 or 50 years of abuse. You could put a performance one in but it probably isn't necessary.
If that's the case, why would this one be cracked? Not doubting what you say, but if mine (which looks OEM) is cracked, I would like to know the root cause and address it.
Also something to do while it's on the lift, service the transmission. (Fluid, filter, and gasket)

Whilst I whole-heartedly agree, it got nearly 2 services in a row right at 5k miles ago. I changed the fluid, filter and adjusted the bands. And then dealt with more leakage than I could tolerate afterwards. Went back again and I changed the old leaky pan, pan gasket, and of course the fluid somewhat soon thereafter. The trans worked good before, and better after the band adjustments. Previous to this maintenance, when easing up to speed, the 2-3 shift would sometimes start to happen, then it would "decide" not to, and repeat like that a couple times sometimes. But since the adjustment, it shifts crisp 2-3 under light throttle. Medium to WOT it always shifted well and still does. And when I check the fluid level now, it's such a pretty red color, it makes me smile that such an old transmission runs so well and clean. Should I do it again anyway?