OK, we've got numbers.

Gross weight front axle: #1860

Less 2 wheels @ #43 each: #1774

Spring length control arm level: 9-3/4" +-

Bushing to spring center: 8-1/2" +-

Bushing to tire center: 17-7/8" +-

Looks like the Speedway site would call for #425 springs although, at this point, I'm very tempted to order #450's and trim until I get it just where I want it.