Will,
I would "imagine" you will be okay, but as to ride quality, you are running 100lb harder springs than me . On my Sapphire I found even 400lb springs too hard for the road (fine on A-roads / motorway), but too stiff on bumpy B-roads.

So when you get your car up and running, I would be VERY interested in hearing how you got on .

In the meantime, regarding the comments about the rear ARB, I know that mine needs stiffening up, but I want to get the front sorted first (so I know where I'm at with what I want to do with the rear). For information, the from uses a roll bar stiffness of 614656 (28mm) and the rear 234256 (22mm), so if anyone has any figures for the bladed ones?