Landrum spring adjusters (or equivalent)?

[Poochie]

Good day all.

I'm in the process of upgrading the front end of my '69 Firebird. I'm going with the Speedtech upper and lower arms, and probably the Touring Classics C5 brake kit. I'm also going to replace the front springs. Since this is a Pontiac engine, I was considering something like the Hyperco 5"x9.5" 650 or 700 lbs/in springs. I would like to use something like the Landrum LSS320 spring adjuster as well (I got this part number from Mr. Pozzi's website), but Landrum doesn't make them anymore. Is there an equivalent type of product out there? And does my choice of spring rate seem to be in the ball park? The car is primarily a weekend warrior, but autocross and/or the odd track day is in it's future.

Thanks in advance for any advice.

Cheers,
Ken