How much you gonna put in the trunk?
I don't have the 555's, but a couple people I know like them.
I could tell you whats in the trunk but...
Tall tire fits on the back of my Barracuda. I've got 28.5" tall 295/45/18s on the back of mine with stock wells/axle housing. I'd keep it tall for aesthetics.
I have 555's, they're old now, but haven't given me any trouble.
I contacted Nitto yesterday and they said for a 1970 big block the minimum load index spec is 95. Of course, the Nitto 555 255/45/17 you have, and I was also hoping to use up front, are 92 load index
I don't fully understand the drawbacks but maybe if you haven't had problems its ok??
The Kumho Ecsta SPT does seem to be an alternative with higher load index...
As far as keeping it tall, at 27" dia., as far as I can tell the 255/50 is about as good as it gets in a 17" wheel. Nitto 450 has a 275/50 but the corresponding front would have to be 255/50, which from what I've read here is too much for the front...
While I have you here, I think you guys run disc brakes in front, if I convert from drum to disc should I expect any wheel fittment issues? The 17x8 year one rallye's actually have 4.25" backspace so if that's going to be a problem it would probably force me to go with the 9"...