Hi Slarti, nice to see you're still beavering away in the background.
I uprated my arb to the late spit thicker bar after removing another leaf from the rear spring and fitting 150lb front springs. This has given me an agreeable compromise between ride and handling - it now feels more like a taught road car than a rock hard racer - and you can actually drive it faster on the road because it's no longer thrown off line by mid corner bumps. There's still almost no roll in the bends and the front tyres are a lot less likely to skid under heavy braking as the front end now just squats down a couple of inches and grips.
As you're using a lighter engine it's probably a good idea to try it with everything you've already got first, then make changes if you want a softer/harder ride later. Everything's easy to get to and the parts are cheap so it wouldn't be a problem to make retrospective changes.
Having said that, assuming you have a standard rear spring stack and not a swing-spring, I would recommend you take the top three 'loose' leaves out, plus another leaf from the next stack down while the body's off the chassis. Trust me, your knuckles will thank you for it later!
With 175/80/14 tyres that will give you the correct ride height at the back without needing a lowering block and endow the rear axle with a firm, rather than bone jarring ride.
A lot of people get seduced by talk of 'uprated' 330lb springs and expensive, branded shocks. imho there's no need to spend loads on the suspension on these cars, they're so light and low that they handle really well on Standard (pun intended) shocks and springs.
Good luck.
